This extraordinary complex was constructed between the years 118 and 134 AD at the foot of Tibur - today's Tivoli - a town founded in the 9th century BC. Only one fifth of the 300 hectares that originally occupied the site are visible today. The complex includes a porticoed entrance called "the Poecile", a building with three exedras, small and large thermal baths, the Canopus pool, the Imperial Palace and the maritime theater. The villa was declared a World Heritage site by UNESCO in 1999.