Machu Picchu is located at an altitude of about 7,970 feet (2,430 meters) above sea level and spans approximately 32,592 acres (13,000 hectares). The city was constructed in the 15th century and remained undiscovered by outsiders until 1911. Machu Picchu features over 200 structures, including temples, terraces, and living quarters, with the most famous being the Intihuatana stone, an ancient ritual stone associated with astronomy. It attracts around 1.5 million visitors annually.