1: Machu Picchu (Quechua: Machu Pikchu, "Old Peaks") is a pre-Columbian 15th-century Inca site located 2,430 metres (7,970 ft) above sea level. It is situated on a mountain ridge above the Urubamba Valley in Peru, which is 80 kilometres (50 mi) northwest of Cusco and through which the Urubamba River flows. Most archaeologists believe that Machu Picchu was built as an estate for the Inca emperor Pachacuti (1438–1472). Often referred to as "The Lost City of the Incas", it is perhaps the most familiar icon of the Inca World.
2: The Incas started building the "estate" around AD 1400 but abandoned it as an official site for the Inca rulers a century later at the time of the Spanish Conquest. Although known locally, it was unknown to the outside world before being brought to international attention in 1911 by the American historian Hiram Bingham. Since then, Machu Picchu has become an important tourist attraction. Since the site was never known to the Spanish during their conquest, it is highly significant as a relatively intact cultural site.
3: Machu Picchu was built in the classical Inca style, with polished dry-stone walls. Its three primary buildings are the Intihuatana, the Temple of the Sun, and the Room of the Three Windows. These are located in what is known by archaeologists as the Sacred District of Machu Picchu. In September 2007, Peru and Yale University almost reached an agreement regarding the return of artifacts which Yale has held since Hiram Bingham removed them from Machu Picchu in the early 20th century. In November 2010.
4: Iguazu Falls, Iguassu Falls, or Iguau Falls (Portuguese: Cataratas do Iguau [kataatz du iwasu]; Spanish: Cataratas del Iguazú [kataataz el iwasu]; Guarani: Chororo Yguasu [ooo asu]) are waterfalls of the Iguazu River located on the border of the Brazilian State of Paraná and the Argentine Province of Misiones. The falls divide the river into the upper and lower Iguazu. The Iguazu River starts at the city of Curitiba and runs for the most part of the course in Brazil and at the end at the border of Brazil and Argentina.
5: Their name comes from the Guarani or Tupi words y  (water) and asú [wasu] (big). Legend has it that a god planned to marry a beautiful woman named Naipí, who fled with her mortal lover Tarobá in a canoe. In rage the god sliced the river, creating the waterfalls and condemning the lovers to an eternal fall. The first European to find the falls was the Spanish Conquistador Álvar Núñez Cabeza de Vaca in 1541, after whom one of the falls on the Argentine side is named.The falls were rediscovered by Boselli at the end of the nineteenth century, and one of the Argentine falls is named after him.
7: Upon seeing Iguazu, the United States' First Lady Eleanor Roosevelt reportedly exclaimed "Poor Niagara!" Iguazu is also often compared with Southern Africa's Victoria Falls which separates Zambia and Zimbabwe. Iguazu is wider, but because it is split into about 275 discrete falls and large islands, Victoria is the largest curtain of water in the world. With the flooding of the Guaíra Falls in 1982, Iguazu currently has the second greatest average annual flow of any waterfall in the world, after Niagara, with an average rate of 1,746 m3/s. Mist rises between 30 metres (98 ft) and 150 m (492 ft) from Iguazu's Devil's Throat, and over 300 m (984 ft) above Victoria. However, Iguazu affords better views and walkways and its shape allows for spectacular vistas. At one point a person can stand and be surrounded by 260 degrees of waterfalls. The Devil's Throat, in Argentina, has water pouring into it from three sides. Likewise, because Iguazu is split into many relatively small falls, one can view these a portion at a time. Victoria does not allow this, as it is essentially one waterfall that falls into a canyon and is too immense to appreciate at once (except from the air). Iguazu Falls was short-listed as a candidate to be one of the New 7 Wonders of Nature by the New Seven Wonders of the World Foundation.
8: he Taj Mahal from Persian/Urdu: "crown of buildings",is a mausoleum located in Agra, India. It is one of the most recognizable structures in the world. It was built by Mughal emperor Shah Jahan in memory of his third wife, Mumtaz Mahal. It is widely considered as one of the most beautiful buildings in the world and stands as a symbol of eternal love. Taj Mahal is the finest example of Mughal architecture, a style that combines elements from Persian, Islamic and Indian architectural styl | In 1983, the Taj Mahal became a UNESCO World Heritage Site. While the white domed marble mausoleum is the most familiar component of the Taj Mahal, it is actually an integrated complex of structures. The construction began around 1632 and was completed around 1653, employing thousands of artisans and craftsmen. The construction of the Taj Mahal was entrusted to a board of architects under imperial supervision, including Abd ul-Karim Ma'mur Khan, Makramat Khan, and Ustad Ahmad Lahauri. Lahauri is generally considered to be the principal designer.
9: The Taj Mahal incorporates and expands on design traditions of Persian architecture and earlier Mughal architecture. Specific inspiration came from successful Timurid and Mughal buildings including; the Gur-e Amir (the tomb of Timur, progenitor of the Mughal dynasty, in Samarkand),Humayun's Tomb, Itmad-Ud-Daulah's Tomb (sometimes called the Baby Taj), and Shah Jahan's own Jama Masjid in Delhi. While earlier Mughal buildings were primarily constructed of red sandstone, Shah Jahan promoted the use of white marble inlaid with semi-precious stones, and buildings under his patronage reached new levels of refinement.
11: In 1631, Shah Jahan, emperor during the Mughal empire's period of greatest prosperity, was grief-stricken when his third wife, Mumtaz Mahal, died during the birth of their 14th child, Gauhara Begum.Construction of the Taj Mahal began in 1632, one year after her death. The court chronicles of Shah Jahan's grief illustrate the love story traditionally held as an inspiration for Taj Mahal. The principal mausoleum was completed in 1648 and the surrounding buildings and garden were finished five years later. Emperor Shah Jahan himself described the Taj in these words: Should guilty seek asylum here, Like one pardoned, he becomes free from sin. Should a sinner make his way to this mansion, All his past sins are to be washed away. The sight of this mansion creates sorrowing sighs; And the sun and the moon shed tears from their eyes. In this world this edifice has been made; To display thereby the creator's glory.
12: The Grand Canyon is a steep-sided canyon carved by the Colorado River in the United States in the state of Arizona. It is largely contained within the Grand Canyon National Park, one of the first national parks in the United States. President Theodore Roosevelt was a major proponent of preservation of the Grand Canyon area, and visited it on numerous occasions to hunt and enjoy the scenery. Nearly two billion years of the Earth's geological history have been exposed as the Colorado River and its tributaries cut their channels through layer after layer of rock while the Colorado Plateau was uplifted.While the specific geologic processes and timing that formed the Grand Canyon are the subject of debate by geologists, Before European immigration, the area was inhabited by Native Americans who built settlements within the canyon and its many caves. The Pueblo people considered the Grand Canyon ("Ongtupqa" in Hopi language) a holy site and made pilgrimages to it.
13: About 600 deaths have occurred in the Grand Canyon since the 1870s. Some of these deaths occurred as the result of overly zealous photographic endeavors, some were the result of airplane collisions within the canyon, and some visitors drowned in the Colorado River. Many hikers overestimate their fitness level, become dehydrated and confused, and must be rescued. The Park Service now posts a picture of an attractive and fit young man at several trailheads with the caption "Every year we rescue hundreds of people from the Canyon. Most of them look like him", in an attempt to discourage hikers from feats which are beyond their abilities.
14: The Egyptian pyramids are ancient pyramid-shaped masonry structures located in Egypt. There are 138 pyramids discovered in Egypt as of 2008. Most were built as tombs for the country's Pharaohs and their consorts during the Old and Middle Kingdom periods. The earliest known Egyptian pyramids are found at Saqqara, northwest of Memphis. The earliest among these is the Pyramid of Djoser which was built during the third dynasty. This pyramid and its surrounding complex were designed by the architect Imhotep, and are generally considered to be the world's oldest monumental structures constructed of dressed masonry. The most famous Egyptian pyramids are those found at Giza, on the outskirts of Cairo. Several of the Giza pyramids are counted among the largest structures ever built. The Pyramid of Khufu at Giza is the largest Egyptian pyramid. It is the only one of the Seven Wonders of the Ancient World still in existence.
15: By the time of the early dynastic period of Egyptian history, those with sufficient means were buried in bench-like structures known as mastabas. The second historically documented Egyptian pyramid is attributed to the architect Imhotep, who planned what Egyptologists believe to be a tomb for the pharaoh Djoser. Imhotep is credited with being the first to conceive the notion of stacking mastabas on top of each other — creating an edifice composed of a number of "steps" that decreased in size towards its apex. The result was the Step Pyramid of Djoser — which was designed to serve as a gigantic stairway by which the soul of the deceased pharaoh could ascend to the heavens. Such was the importance of Imhotep's achievement that he was deified by later Egyptians
17: The most prolific pyramid-building phase coincided with the greatest degree of absolutist pharaonic rule. It was during this time that the most famous pyramids, those near Giza, were built. Over time, as authority became less centralized, the ability and willingness to harness the resources required for construction on a massive scale decreased, and later pyramids were smaller, less well-built and often hastily constructed. Long after the end of Egypt's own pyramid-building period, a burst of pyramid-building occurred in what is present-day Sudan, after much of Egypt came under the rule of the Kings of Napata. While Napatan rule was brief and ceased in 661 BC, the Egyptian influence made an indelible impression, and during the later Sudanese Kingdom of Meroe this flowered into a full-blown pyramid-building revival, which saw more than two hundred indigenous, but Egyptian-inspired royal pyramid-tombs constructed in the vicinity of the kingdom's capital cities. Al-Aziz Uthman, son of the great Saladin who crushed the Crusaders, tried to demolish the Great pyramids of Giza, but had to give up because the task was too big. He found it almost as expensive to destroy as to build. However, he did succeed in damaging Menkaure's pyramid
18: The Serengeti ecosystem is a geographical region located in north-western Tanzania and extends to south-western Kenya between latitudes 1 and 3 S and longitudes 34 and 36 E. It spans some 30,000 km2 (12,000 sq mi). The Serengeti hosts the largest mammal migration in the world, which is one of the ten natural travel wonders of the world. The region contains several national parks and game reserves. Serengeti is derived from the Maasai language, Maa; specifically, "Serengit" meaning "Endless Plains". Approximately 70 larger mammal and some 500 avifauna species are found there. This high diversity in terms of species is a function of diverse habitats ranging from riverine forests, swamps, kopjes, grasslands and woodlands. Blue Wildebeests, gazelles, zebras and buffalos are some of the commonly found large mammals in the region. Currently there is controversy surrounding a proposed road that is to be built through the Serengeti in Tanzania
19: Much of the Serengeti was known to outsiders as Maasailand. The Maasai were known as fierce warriors, and lived alongside most wild animals with an aversion to eating game and birds, subsisting exclusively on their cattle. Their strength and reputation kept the newly arrived Europeans from exploiting the animals and resources of most of their land. A rinderpest epidemic and drought during the 1890s greatly reduced the numbers of both Maasai and animal populations. Poaching and the absence of fires, which had been the result of human activity, set the stage for the development of dense woodlands and thickets over the next 30–50 years. Tsetse fly populations now prevented any significant human settlement in the area.Fire, elephants, and wildebeest were influential in determining the current character of the Serengeti. By the 1960s, as human populations increased, fire, either intentionally set by the Maasai to increase area available for pasture, or accidentally, scorched new tree seedlings. Heavy rainfall encouraged the growth of grass, which served as fuel for the fires during the following dry seasons.
20: Around October, nearly two million herbivores travel from the northern hills toward the southern plains, crossing the Mara River, in pursuit of the rains. In April, they then return to the north through the west, once again crossing the Mara River. This phenomenon is sometimes called the Circular Migration. Some 250,000 wildebeest die during the journey from Tanzania to Maasai Mara Reserve in lower Kenya, a total of 800 kilometres (500 mi). Death is usually from thirst, hunger, exhaustion, or predation. The migration is chronicled in the 1994 documentary film, Africa: The Serengeti. On early 2007 J.Michael Fay had found another large migration in Southern Sudan, there are about 800,000 kob and tiang which nows rivals the one in the Serengeti.
21: Petra (Greek "" (petra), meaning rock; Arabic: , Al-Batr) is a historical and archaeological city in the Jordanian governorate of Ma'an that is known for its rock cut architecture and water conduits system. Established sometime around the 6th century BC as the capital city of the Nabataean.it is a symbol of Jordan as well as its most visited tourism attraction. It lies on the slope of Mount Hor in a basin among the mountains which form the eastern flank of Arabah (Wadi Araba), the large valley running from the Dead Sea to the Gulf of Aqaba. Petra has been a UNESCO World Heritage Site since 1985. The site remained unknown to the Western world until 1812, when it was introduced by Swiss explorer Johann Ludwig Burckhardt. It was described as "a rose-red city half as old as time" in a Newdigate Prize-winning sonnet by John William Burgon. UNESCO has described it as "one of the most precious cultural properties of man's cultural heritage." Petra was chosen by the BBC as one of "the 40 places you have to see before you die
22: Evidence suggests that settlements had begun in and around Petra in the eighteenth dynasty of Egypt (1550-1292 BC). It is listed in Egyptian campaign accounts and the Amarna letters as Pel, Sela or Seir. Though the city was founded relatively late, a sanctuary existed there since very ancient times. Stations 19 through 26 of the stations list of Exodus are places associated with PetraThis part of the country was Biblically assigned to the Horites, the predecessors of the Edomites. The habits of the original natives may have influenced the Nabataean custom of burying the dead and offering worship in half-excavated caves. Although Petra is usually identified with Sela which means a rock, the Biblical references refer to it as "the cleft in the rock", referring to its entrance. The second book of Kings xiv. 7 seems to be more specific. In the parallel passage, however, Sela is understood to mean simply "the rock". | On the authority of Josephu Eusebius and Jerome assert that Rekem was the native name and Rek em appears in the Dead Sea Scrolls as a prominent Edom site most closely describing Petra and associated with Mount Seir. But in the Aramaic versions Rekem is the name of Kadesh, implying that Josephus may have confused the two places. Sometimes the Aramaic versions give the form Rekem-Geya which recalls the name of the village El-ji, southeast of Petra. | the "petra" referred to as a natural fortress and place of refuge cannot be a proper name and the description implies that the town was not yet in existence. The only place in Petra where the name "Rekem" occurs was in the rock wall of the Wadi Musa opposite the entrance to the Siq. About twenty years ago the Jordanians built a bridge over the wadi and this inscription was buried beneath tons of concrete.
23: On December 6, 1985, Petra was designated a World Heritage Site. In 2006 the design of a Visitor Centre began. The Jordan Times reported in December 2006 that 59,000 people visited in the two months October and November 2006, 25% fewer than the same period in the previous year.
24: The Great Wall of China is a series of stone and earthen fortifications in northern China, built originally to protect the northern borders of the Chinese Empire against intrusions by various nomadic groups. Several walls have been built since the 5th century BC that are referred to collectively as the Great Wall, which has been rebuilt and maintained from the 5th century BC through the 16th century. One of the most famous is the wall built between 220–206 BC by the first Emperor of China, Qin Shi Huang. Little of that wall remains; the majority of the existing wall was built during the Ming Dynasty.
25: The Great Wall stretches from Shanhaiguan in the east, to Lop Nur in the west, along an arc that roughly delineates the southern edge of Inner Mongolia. The most comprehensive archaeological survey, using advanced technologies, has concluded that the entire Great Wall, with all of its branches, stretches for 8,851.8 km (5,500.3 mi). This is made up of 6,259.6 km (3,889.5 mi) sections of actual wall, 359.7 km (223.5 mi) of trenches and 2,232.5 km (1,387.2 mi) of natural defensive barriers such as hills and rivers.
26: Qin Shi Huang conquered all opposing states and unified China in 221 BC, establishing the Qin Dynasty. Intending to impose centralized rule and prevent the resurgence of feudal lords, he ordered the destruction of the wall sections that divided his empire along the former state borders. To protect the empire against intrusions by the Xiongnu people from the north, he ordered the building of a new wall to connect the remaining fortifications along the empire's new northern frontier. Transporting the large quantity of materials required for construction was difficult, so builders always tried to use local resources. Stones from the mountains were used over mountain ranges, while rammed earth was used for construction in the plains. There are no surviving historical records indicating the exact length and course of the Qin Dynasty walls. Most of the ancient walls have eroded away over the centuries, and very few sections remain today. Later, the Han, Sui, Northern and Jin dynasties all repaired, rebuilt, or expanded sections of the Great Wall at great cost to defend themselves against northern invaders. It is estimated that over 1 million workers died building the wall.
27: While some portions north of Beijing and near tourist centers have been preserved and even extensively renovated, in many locations the Wall is in disrepair. Those parts might serve as a village playground or a source of stones to rebuild houses and roads. Sections of the Wall are also prone to graffiti and vandalism. Parts have been destroyed because the Wall is in the way of construction. More than 60 km (37 mi) of the wall in Gansu province may disappear in the next 20 years, due to erosion from sandstorms. In places, the height of the wall has been reduced from more than five meters (16.4 ft) to less than two meters. The square lookout towers that characterize the most famous images of the wall have disappeared completely. Many western sections of the wall are constructed from mud, rather than brick and stone, and thus are more susceptible to erosion. Communication between the army units along the length of the Great Wall, including the ability to call reinforcements and warn garrisons of enemy movements, was of high importance. Signal towers were built upon hill tops or other high points along the wall for their visibility.
28: The VThe Victoria Falls are some of the most famous, considered by some to be among the Seven Natural Wonders of the World. David Livingstone, the Scottish missionary and explorer, is believed to have been the first European recorded to view the Victoria Falls — which he did from what is now known as 'Livingstone Island' in Zambia, the only land accessible in the middle of the falls. David Livingstone gave the falls the name 'Victoria Falls' in honour of his Queen, but the indigenous name of 'Mosi-oa-Tunya' — literally meaning the 'Smoke that Thunders' — is also well known. The World Heritage List recognizes both names. While it is neither the highest nor the widest waterfall in the world, it is claimed to be the largest. This claim is based on a width of 1,708 metres and height of 108 metres, forming the largest sheet of falling water in the world. The falls are some of the largest in the world.
29: The recent geological history of Victoria Falls can be seen in the form of the gorges below the falls. The basalt plateau over which the Upper Zambezi flows has many large cracks filled with weaker sandstone. In the area of the current falls the largest cracks run roughly east to west (some run nearly north-east to south-west), with smaller north-south cracks connecting them. Over at least 100,000 years, the falls have been receding upstream through the Batoka Gorges, eroding the sandstone-filled cracks to form the gorges. The river's course in the current vicinity of the falls is north to south, so it opens up the large east-west cracks across its full width, then it cuts back through a short north-south crack to the next east-west one. The river has fallen in different eras into different chasms which now form a series of sharply zig-zagging gorges downstream from the falls.
30: Ignoring some dry sections, the Second to Fifth and the Songwe Gorges each represents a past site of the falls at a time when they fell into one long straight chasm as they do now. Their sizes indicate that we are not living in the age of the widest-ever falls. The falls have already started cutting back the next major gorge, at the dip in one side of the "Devil's Cataract" (also known as "Leaping Waters") section of the falls. This is not actually a north-south crack, but a large east-northeast line of weakness across the river, where the next full-width falls will eventually form. Further geological history of the course of the Zambezi River is in the article of that name.
31: Archaeological sites around the falls have yielded Homo habilis stone artifacts from 3 million years ago, 50,000-year-old Middle Stone Age tools and Late Stone Age (10,000 and 2,000 years ago) weapons, adornments and digging tools. Iron-using Khoisan hunter-gatherers displaced these Stone Age people and in turn were displaced by Bantu tribes such as the southern Tonga people known as the Batoka/Tokalea, who called the falls Shungu na mutitima. The Matabele, later arrivals, named them aManz' aThunqayo, and the Batswana and Makololo (whose language is used by the Lozi people) call them Mosi-o-Tunya. All these names mean essentially "the smoke that thunders". The first European to see the falls was David Livingstone on 17 November 1855, during his 1852–56 journey from the upper Zambezi to the mouth of the river. The falls were well known to local tribes, and Voortrekker hunters may have known of them, as may the Arabs under a name equivalent to "the end of the world". Europeans were sceptical of their reports, perhaps thinking that the lack of mountains and valleys on the plateau made a large falls unlikely. Livingstone had been told about the falls before he reached them from upriver and was paddled across to a small island that now bears the name Livingstone Island in Zambia. Livingstone had previously been impressed by the Ngonye Falls further upstream, but found the new falls much more impressive, and gave them their English name in honour of Queen Victoria. He wrote of the falls, "No one can imagine the beauty of the view from anything witnessed in England. It had never been seen before by European eyes; but scenes so lovely must have been gazed upon by angels in their flight." In 1860, Livingstone returned to the area and made a detailed study of the falls with John Kirk. Other early European visitors included Portuguese explorer Serpa Pinto, Czech explorer Emil Holub, who made the first detailed plan of the falls and its surroundings in 1875 (published in 1880), and British artist Thomas Baines, who executed some of the earliest paintings of the falls. Until the area was opened up by the building of the railway in 1905, though, the falls were seldom visited by other Europeans.
32: The Great Barrier Reef is the world's largest reef system composed of over 2,900 individual reefs and 900 islands stretching for over 2,600 kilometres (1,600 mi) over an area of approximately 344,400 square kilometres (133,000 sq mi). The reef is located in the Coral Sea, off the coast of Queensland in north-east Australia. The Great Barrier Reef can be seen from outer space and is the world's biggest single structure made by living organisms. This reef structure is composed of and built by billions of tiny organisms, known as coral polyps. This reef supports a wide diversity of life, and was selected as a World Heritage Site in 1981. CNN labeled it one of the seven natural wonders of the world. The Queensland National Trust named it a state icon of Queensland.
33: A large part of the reef is protected by the Great Barrier Reef Marine Park, which helps to limit the impact of human use, such as fishing and tourism. Other environmental pressures on the reef and its ecosystem include runoff, climate change accompanied by mass coral bleaching, and cyclic population outbreaks of the crown-of-thorns starfish. The Great Barrier Reef has long been known to and used by the Aboriginal Australian and Torres Strait Islander peoples, and is an important part of local groups' cultures and spirituality. The reef is a very popular destination for tourists, especially in the Whitsunday Islands and Cairns regions. Tourism is an important economic activity for the region, generating A$ 1 billion per year.
34: The Great Barrier Reef has long been known to and used by the Aboriginal Australian and Torres Strait Islander peoples. Aboriginal Australians have been living in the area for at least 40,000 years, and Torres Strait Islanders since about 10,000 years ago. For these 70 or so clan groups, the reef is also an important cultural feature. In 1768, Louis de Bougainville found the reef during an exploratory mission, but did not claim the area for the French. On June 11, 1770, the HM Bark Endeavour, captained by explorer James Cook, ran aground on the Great Barrier Reef, sustaining considerable damage. Lightening the ship and re-floating it during an incoming tide eventually saved it. One of the most famous wrecks was the HMS Pandora, which sank on August 29, 1791, killing 35. The Queensland Museum has led archaeological digs to the Pandora since 1983. Because the reef had no atolls, it was largely unstudied in the 19th century. During this time, some of the reef's islands were mined for deposits of guano, and lighthouses were built as beacons throughout the system. as in Raine Island, the earliest example. In 1922, the Great Barrier Reef Committee began carrying out much of the early research on the reef.
35: Due to its vast biodiversity, warm clear waters and accessibility from the tourist boats called 'live aboards', the reef is a very popular destination, especially for scuba divers. Tourism on the Great Barrier Reef is concentrated in the Whitsundays and Cairns due to their accessibility. These areas make up 7% of the Park's area. The Whitsundays and Cairns have their own Plans of Management. Many cities along the Queensland coast offer daily boat trips. Several continental and coral cay islands are now resorts, including the pristine Lady Elliot Island. As of 1996, 27 islands on the Great Barrier Reef supported resorts Domestic tourism made up most of the tourism in the region as of 1996, and the most popular visiting times were in the Australian winter. It was estimated that tourists to the Great Barrier Reef contributed A$776 million per annum at this time.
36: Angkor (Khmer: ) is a region of Cambodia that served as the seat of the Khmer Empire, which flourished from approximately the 9th to 13th centuries. The word Angkor is derived from the Sanskrit nagara (), meaning "city". The Angkorian period began in AD 802, when the Khmer Hindu monarch Jayavarman II declared himself a "universal monarch" and "god-king", until 1431, when Ayutthayan invaders sacked the Khmer capital, causing its population to migrate south to the area of Phnom Penh. The ruins of Angkor are located amid forests and farmland to the north of the Great Lake (Tonlé Sap) and south of the Kulen Hills, near modern-day Siem Reap (1324N, 10351E), and are a UNESCO World Heritage Site. The temples of the Angkor area number over one thousand, ranging in scale from nondescript piles of brick rubble scattered through rice fields to the magnificent Angkor Wat, said to be the world's largest single religious monument.
37: Many of the temples at Angkor have been restored, and together, they comprise the most significant site of Khmer architecture. Visitor numbers approach two million annually. In 2007, an international team of researchers using satellite photographs and other modern techniques concluded that Angkor had been the largest preindustrial city in the world, with an elaborate system of infrastructure connecting an urban sprawl of at least 1000 square kilometres to the well-known temples at its core. The closest rival to Angkor, the Mayan city of Tikal in Guatemala, was between 100 and 150 square kilometres in total size. Although its population remains a topic of research and debate, newly identified agricultural systems in the Angkor area may have supported up to one million people.
38: The great city and temples remained largely cloaked by the forest until the late 19th century, when French archaeologists began a long restoration process. From 1907 to 1970, work was under the direction of the École franaise d'Extrme-Orient, which cleared away the forest, repaired foundations, and installed drains to protect the buildings from water damage. In addition, scholars associated with the school and including George Coeds, Maurice Glaize, Paul Mus, Philippe Stern and others initiated a program of historical scholarship and interpretation that is fundamental to the current understanding of Angkor. Work resumed after the end of the Cambodian civil war and, since 1993, has been jointly co-ordinated by the French, Japanese and UNESCO through the International Co-ordinating Committee on the Safeguarding and Development of the Historic Site of Angkor (ICC), while Cambodian work is carried out by the Authority for the Protection and Management of Angkor and the Region of Siem Reap (APSARA), created in 1995.
39: Some temples have been carefully taken apart stone by stone and reassembled on concrete foundations, in accordance with the method of anastylosis. World Monuments Fund has aided Preah Khan, the Churning of the Sea of Milk (a 49-meter-long bas-relief frieze in Angkor Wat), Ta Som, and Phnom Bakheng. International tourism to Angkor has increased significantly in recent years, with visitor numbers reaching 900,000 in 2006; this poses additional conservation problems but has also provided financial assistance to the restoration effort. Water-table dropping With the increased growth in tourism at Angkor, new hotels and restaurants are being built to accommodate such growth. Each new construction project drills underground to reach the water table, which has a limited storage capacity. This demand on the water table could undermine the stability of the sandy soils under the monuments at Angkor, leading to cracks, fissures and collapses.
40: The Amazon Rainforest (in Portuguese, Floresta Amaznica or Amaznia; Spanish: Selva Amazónica or Amazonia; French: Fort amazonienne; Dutch: Amazoneregenwoud), also known as Amazonia or Amazon Jungle, is a moist broadleaf forest that covers most of the Amazon Basin of South America. This basin encompasses seven million square kilometers (1.7 billion acres), of which five and a half million square kilometers (1.4 billion acres) are covered by the rainforest. This region includes territory belonging to nine nations. The majority of the forest is contained within Brazil, with 60% of the rainforest, followed by Peru with 13%, and with minor amounts in Colombia, Venezuela, Ecuador, Bolivia, Guyana, Suriname and French Guiana. States or departments in four nations bear the name Amazonas after it. The Amazon represents over half of the planet's remaining rainforests, and it comprises the largest and most species-rich tract of tropical rainforest in the world. The Amazon rainforest was short-listed in 2008 as a candidate to one of the New7Wonders of Nature by the New Seven Wonders of the World Foundation. As of February 2009 the Amazon was ranking first in Group E, the category for forests, national parks and nature reserves.
41: The rainforest likely formed during the Eocene era. It appeared following a global reduction of tropical temperatures when the Atlantic Ocean had widened sufficiently to provide a warm, moist climate to the Amazon basin. The rain forest has been in existence for at least 55 million years, and most of the region remained free of savanna-type biomes at least until the current ice age, when the climate was drier and savanna more widespread. Following the Cretaceous–Tertiary extinction event, the extinction of the dinosaurs and the wetter climate may have allowed the tropical rainforest to spread out across the continent. From 65–34 Mya, the rainforest extended as far south as 45. Climate fluctuations during the last 34 million years have allowed savanna regions to expand into the tropics. During the Oligocene, for example, the rainforest spanned a relatively narrow band that lay mostly above latitude 15N. It expanded again during the Middle Miocene, then retracted to a mostly inland formation at the last glacial maximum. However, the rainforest still managed to thrive during these glacial periods, allowing for the survival and evolution of a broad diversity of species.
42: Based on archaeological evidence from an excavation at Caverna da Pedra Pintada, human inhabitants first settled in the Amazon region at least 11,200 years ago. Subsequent development led to late-prehistoric settlements along the periphery of the forest by 1250 AD, which induced alterations in the forest cover. Biologists believe that a population density of 0.2 inhabitants per square kilometre (0.52 /sq mi) is the maximum that can be sustained in the rain forest through hunting. Hence, agriculture is needed to host a larger population. The first European to travel the length of the Amazon River was Francisco de Orellana in 1542.Wet tropical forests are the most species-rich biome, and tropical forests in the Americas are consistently more species rich than the wet forests in Africa and Asia. As the largest tract of tropical rainforest in the Americas, the Amazonian rainforests have unparalleled biodiversity. One in ten known species in the world lives in the Amazon Rainforest. This constitutes the largest collection of living plants and animal species in the world.
43: The diversity of plant species is the highest on Earth with some experts estimating that one square kilometer (247 acres) may contain more than a thousand types of trees and thousands of species of other higher plants. According to a 2001 study, a quarter square kilometer (62 acres) of Ecuadorian rainforest supports more than 1,100 tree species. One square kilometer (247 acres) of Amazon rainforest can contain about 90,790 metric tonnes of living plants. The average plant biomass is estimated at 356 47 tonnes ha1. To date, an estimated 438,000 species of plants of economic and social interest have been registered in the region with many more remaining to be discovered or catalogued.
44: The Niagara Falls are voluminous waterfalls on the Niagara River, straddling the international border between the Canadian province of Ontario and the U.S. state of New York. The falls are 17 miles (27 km) north-northwest of Buffalo, New York and 75 miles (121 km) south-southeast of Toronto, Ontario, between the twin cities of Niagara Falls, Ontario, and Niagara Falls, New York. Niagara Falls is composed of two major sections separated by Goat Island: the Horseshoe Falls, which today is entirely on the Canadian side of the border, and the American Falls on the American side. The smaller Bridal Veil Falls are also located on the American side, separated from the main falls by Luna Island.
45: Niagara Falls were formed when glaciers receded at the end of the Wisconsin glaciation (the last ice age), and water from the newly formed Great Lakes carved a path through the Niagara Escarpment en route to the Atlantic Ocean. While not exceptionally high, the Niagara Falls are very wide. More than 6 million cubic feet (168,000 m3) of water falls over the crest line every minute in high flow, and almost 4 million cubic feet (110,000 m3) on average. It is the most powerful waterfall in North America. The Niagara Falls are renowned both for their beauty and as a valuable source of hydroelectric power. Managing the balance between recreational, commercial, and industrial uses has been a challenge for the stewards of the falls since the 19th century.
47: Niagara Falls is divided into the Horseshoe Falls and the American Falls. The Horseshoe Falls drop about 173 feet (53 m), and the height of the American Falls varies between 70–100 feet (21–30 m) because of the presence of giant boulders at its base. The larger Horseshoe Falls are about 2,600 feet (790 m) wide, while the American Falls are 1,060 feet (320 m) wide. The volume of water approaching the falls during peak flow season may sometimes be as much as 202,000 cubic feet (5,700 m3) per second. Since the flow is a direct function of the Lake Erie water elevation, it typically peaks in late spring or early summer. During the summer months, 100,000 cubic feet (2,800 m3) per second of water actually traverses the falls, some 90% of which goes over the Horseshoe Falls, while the balance is diverted to hydroelectric facilities. This is accomplished by employing a weir with movable gates upstream from the Horseshoe Falls. The falls flow is further halved at night, and during the low tourist season in the winter, remains a flat 50,000 cubic feet (1,400 m3) per second. Water diversion is regulated by the 1950 Niagara Treaty and is administered by the International Niagara Board of Control (IJC). Viewpoints on the American shore generally are astride or behind the falls. The falls face directly toward the Canadian shore. Peak numbers of visitors occur in the summertime, when Niagara Falls are both a daytime and evening attraction. From the Canadian side, floodlights illuminate both sides of the falls for several hours after dark (until midnight). The number of visitors in 2008 is expected to total 20 million and by 2009, the annual rate is expected to top 28 million tourists a year. The oldest and best known tourist attraction at Niagara Falls is the Maid of the Mist boat cruise, named for an ancient Ongiara Indian mythical character, which has carried passengers into the rapids immediately below the falls since 1846. Cruise boats operate from boat docks on both sides of the falls.
48: Salar de Uyuni (or Salar de Tunupa) is the world's largest salt flat at 10,582 square kilometers (4,086 sq mi). It is located in the Potosí and Oruro departments in southwest Bolivia, near the crest of the Andes, and is elevated 3,656 meters (11,995 ft) above the mean sea level. The Salar was formed as a result of transformations between several prehistoric lakes. It is covered by a few meters of salt crust, which has an extraordinary flatness with the average altitude variations within one meter over the entire area of the Salar. The crust serves as a source of salt and covers a pool of brine, which is exceptionally rich in lithium. It contains 50 to 70% of the world's lithium reserves, which is in the process of being extracted. The large area, clear skies and exceptional surface flatness make the Salar an ideal object for calibrating the altimeters of the Earth observation satellites.[ The Salar serves as the major transport route across the Bolivian Altiplano and is a major breeding ground for several species of pink flamingos.
49: Salar de Uyuni is part of the Altiplano of Bolivia in South America. The Altiplano is a high plateau, which was formed during uplift of the Andes mountains. The plateau includes fresh and saltwater lakes as well as salt flats and is surrounded by mountains with no drainage outlets. The geological history of the Salar is associated with a sequential transformation between several vast lakes. Some 30,000–42,000 years ago, the area was part of a giant prehistoric lake, Lake Minchin. Its age was estimated from radiocarbon dating of shells from outcropping sediments and carbonate reefs and varies between reported studies.
50: Lake Minchin (named after the Juan B. Minchin of Oruro) later transformed into paleolake Tauca having a maximal depth of 140 meters (460 ft), and an estimated age of 13,000–18,000 or 14,900–26,100 years depending on the source. The youngest prehistoric lake was Coipasa, which was radiocarbon dated to 11,500–13,400 years. When it dried, it left behind two modern lakes, Poopó Lake and Uru Uru Lake, and two major salt deserts, Salar de Coipasa and the larger Salar de Uyuni. Salar de Uyini spreads over 10,582 square kilometers (4,086 sq mi), which is roughly 25 times the size of the Bonneville Salt Flats in the United States. Lake Poopó is a neighbor of the much larger lake Titicaca. During the wet season, Titicaca overflows and discharges into Poopó, which, in turn, floods Salar De Coipasa and Salar de Uyuni.
51: The Salar is virtually devoid of any wild life and vegetation. The latter is dominated by giant cacti (Echinopsis atacamensis pasacana, Echinopsis tarijensis, etc.). They grow at a rate of about 1 centimeter per year to a length of about 12 meters. Other shrubs include Pilaya, which is used by locals to cure catarrh, and Thola (Baccharis dracunculifolia), which is burned as a fuel. Also present are quinoa plants and quenua bushes. Every November, Salar de Uyuni is the breeding grounds for three species of pink South American flamingos: the Chilean, Andean and rare James's Flamingos, their color presumably originating from feeding on pink algae. There are about 80 of other bird species present, including the horned coot, the Andean goose and the Andean Hillstar. Andean fox (culpeo) is a representative animal, and the "islands" of Salar host a colony of rabbit-like viscachas.
52: Abu Simbel temples refers to two massive rock temples in Abu Simbel ( in Arabic) in Nubia, southern Egypt on the western bank of Lake Nasser about 230 km southwest of Aswan (about 300 km by road). The complex is part of the UNESCO World Heritage Site known as the "Nubian Monuments," which run from Abu Simbel downriver to Philae (near Aswan). The twin temples were originally carved out of the mountainside during the reign of Pharaoh Ramesses II in the 13th century BC, as a lasting monument to himself and his queen Nefertari, to commemorate his alleged victory at the Battle of Kadesh, and to intimidate his Nubian neighbors. However, the complex was relocated in its entirety in 1968, on an artificial hill made from a domed structure, high above the Aswan High Dam reservoir. The relocation of the temples was necessary to avoid their being submerged during the creation of Lake Nasser, the massive artificial water reservoir formed after the building of the Aswan High Dam on the Nile River. Abu Simbel remains one of Egypt's top tourist attractions.
53: Construction of the temple complex started in approximately 1244 BCE. Known as the "Temple of Ramesses, beloved by Amun," it was one of six rock temples erected in Nubia during the long reign of Ramesses II. Their purpose was to impress Egypt's southern neighbors, and also to reinforce the status of Egyptian religion in the region. Historians say that the design of Abu Simbel expresses a measure of ego and pride in Ramesses II With the passage of time, the temples fell into disuse and eventually became covered by sand. The temple was forgotten until 1813, when Swiss orientalist JL Burckhardt found the top frieze of the main temple. Burckhardt talked about his discovery with Italian explorer Giovanni Belzoni, who travelled to the site, but was unable to dig out an entry to the temple. Belzoni returned in 1817, this time succeeding in his attempt to enter the complex. He took everything valuable and portable with him. Tour guides at the site relate the legend that "Abu Simbel" was a young local boy who guided these early re-discoverers to the site of the buried temple which he had seen from time to time in the shifting sands. Eventually, they named the complex after him.
54: It is believed that the axis of the temple was positioned by the ancient Egyptian architects in such a way that on October 21 and February 21, the rays of the sun would penetrate the sanctuary and illuminate the sculptures on the back wall, except for the statue of Ptah, the god connected with the Underworld, who always remained in the dark. These dates are allegedly the king's birthday and coronation day respectively, but there is no evidence to support this, though it is quite logical to assume that these dates had some relation to a great event, such as the jubilee celebrating the thirtieth anniversary of the pharaoh's rule. In fact, according to calculations made on the basis of the heliacal rising of the star Sirius (Sothis) and inscriptions found by archaeologists, this date must have been October 22.
55: This image of the king was enhanced and revitalized by the energy of the solar star, and the deified Ramesses Great could take his place next to Amun Ra and Ra-Horakhty. Due to the displacement of the temple and/or the accumulated drift of the Tropic of Cancer during the past 3,280 years, it is widely believed that each of these two events has moved one day closer to the Solstice, so they would be occurring on October 22 and February 20 (60 days before and 60 days after the Solstice, respectively). The NOAA Solar Position Calculator may be used to verify the declination of the Sun for any location on Earth, at any particular date and time. For the latitude of Abu Simbel 222013N 313732E / 22.33694N 31.62556E / 22.33694; 31.62556, the calculator will yield values close to -11 for both Oct 22 and Feb 20.