Machu Picchu, also known as the “lost city of the Incas”, is visited by many people every year, and is for many travelers the main reason they come to Cuzco. It is a UNESCO world Heritage Site, and one of the seven modern wonders of the world. It is not clearly known why it was built, and since the Incas did not use writing, they left no record. It was probably abandoned in the 16th century, and even though some local residents knew of its existence, it was mostly unknown to the world until 1911. The site is a complex of palaces, plazas, temples and homes.