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 the sun rise. Architecturally, Inti Mach'ay is the most significant structure at Machu Picchu. Its entrances, walls, steps and windows are some of the finest masonry in the Incan Empire. The cave also includes a tunnel-like window unique among Incan structures, which was constructed to only allow sunlight into the cave during several days around the December solstice. For this reason, the cave was inaccessible for much of the year. Inti Mach'ay is located on the eastern side of Machu Picchu, just north of the "Condor Stone." Many of the caves surrounding this area were prehistorically used as tombs, yet