Machu Picchu risks of landslides, earthquakes and injury due to decaying structures. Nude tourism is a recent trend, to the dismay of Peruvian officials. In several incidents, tourists were detained for posing for nude pictures or streaking across the site. Peru's Ministry of Culture denounced these acts for threatening Peru's cultural heritage. Cusco's Regional Director of Culture increased surveillance to end the practice. In January 2010, heavy rain caused flooding that buried or washed away roads and railways to Machu Picchu, trapping more than 2,000 locals and more than 2,000 tourists, later airlifted out to safety. Machu Picchu was temporarily closed, reopening
Machu Picchu an Inca grass rope bridge, across the Urubamba River in the Pongo de Mainique, provided a secret entrance for the Inca army. Another Inca bridge was built to the west of Machu Picchu, the tree-trunk bridge, at a location where a gap occurs in the cliff that measures . The city sits in a saddle between the two mountains Machu Picchu and Huayna Picchu, with a commanding view down two valleys and a nearly impassable mountain at its back. It has a water supply from springs that cannot be blocked easily. The hillsides leading to it were terraced, to provide