The largest Pre-Columbian city in South America, Chan Chan is an archaeological site in the Peruvian region of La Libertad, five km west of Trujillo. Chan Chan covers 20 km² and had a dense urban center of 6 km². Chan Chan was constructed by the Chimor (the kingdom of the Chimú), a late intermediate period civilization which grew out of the remnants of the Moche civilization. The adobe city of Chan Chan, the largest in the world, was built around AD 850 and lasted until its conquest by the Inca Empire in AD 1470. It was the imperial capital where 30,000 people lived.
Chan Chan was added as a UNESCOWorld Heritage Site on November 28 of 1986. The city is severely threatened by storms from El Niño, which cause heavy rains and flooding on the Peruvian coast. It is in a fertile, well-watered section of the coastal plain. The city's ruins are threatened by earthquakes and looters. Visitors to Chan Chan can enter the Tschudi Complex, a later citadel. There are other Chimú and Moche ruins in the area around Trujillo. This site was discovered by conquistadorFrancisco Pizarro.
The first sites within Peru were inscribed on the list at the 7th Session of the World Heritage Committee, held in Florence, Italy in 1983: "City of Cuzco" and the "Historic Sanctuary of Machu Picchu". As of 2010, Peru has 11 sites on the World Heritage List. Seven are listed as cultural sites, two as natural, and two as mixed, meeting both cultural and natural selection criteria, as determined by the organization's selection criteria. Only six of Peru's twenty-five regions are represented, with Ancash, Cuzco, and Lima regions each containing multiple sites.
Peruvian sites have often been subject to extreme weather conditions and disasters. In 1997, a wildfire among the hills adjacent to Machu Picchu threatened the site until fire fighters could cut a ring of trees to prevent the fire from spreading to the ruins. In early 2010, heavy rainfall affected Machu Picchu and Cuzco. On January 25, 2,000 tourists were stranded near Machu Picchu when a landslide blocked the railroad connecting the site with Cuzco. The tourists were evacuated by ten helicopters, including four from the United States military on loan from the embassy in Lima.