In September 2013, a network of tunnels was investigated, buried deep beneath the villa – these were probably service routes for staff so that the idyllic nature of the landscape might remain undisturbed. The site housed several thousand people including staff, visitors, servants and slaves. Although much major activity would have been engaged in during Hadrian's absence on tours of inspection of the provinces a great many people (and animals) must have been moving about the Tivoli site on a daily basis. The almost constant building activity on top of basic gardening and domestic activities probably led to subterranean routes being resorted to.