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 there is no evidence that Mach'ay was a burial ground. The central buildings use the classical Inca architectural style of polished dry-stone walls of regular shape. The Incas were masters of this technique, called ashlar, in which blocks of stone are cut to fit together tightly without mortar. The section of the mountain where Machu Picchu was built provided various challenges that the Incas solved with local materials. One issue was the seismic activity due to two fault lines. It made mortar and similar building methods nearly useless. Instead, the Inca mined stones from the quarry at the site, lined