In the 16th century, the Great Trapezium was identified with the "Underworld" (the Inferi) of Villa Adriana mentioned in the Historia Augusta, and it sparkled the imagination of scholars, such as Giuseppe de' Bardi who described it in the 19th century as «full of infernal mouths, which at will threw fire». There, of course, «lived Cerberus, who at his own will made Hell rumble».
Hadrian stayed only a few times in Villa Adriana, because he was busy traveling throughout the empire. In his last days, being ill, he remained in Baia where he died in 138 AD.
But even if the emperor was not there, Villa Adriana was full of life and activity.
A Court resided there permanently, living in the luxury of the richly decorated noble buildings, and then there were officials, freedmen and praetorians who lived in secondary buildings with less luxurious decorations. And of course there were hundreds of slaves in their service who were housed in more modest buildings, such as the Hundred Chambers or the Praetorium Substructures.
Some slaves were assigned to simple service (such as cooking and cleaning), others were instead engaged in very heavy work, and built one of the most extraordinary structures of Hadrian's Villa: the Great Trapezium.
The Great Trapezium has four immense subterranean galleries with a total length of almost 900 meters, 6 meters high and wide. They were dug by hand into the tuff bank: on the walls you can still see the signs of millions of pickaxes blows given by the slaves who built them. The tuff extracted by them, about thirty thousand cubic meters, was used as building material for the Villa, to make the cubilia and the tuff bricks that can be seen in the walls of the buildings.
The Great Trapezium has never been opened to the public and is partly privately owned. In the vaults of the tunnels 79 large oculi for lighting open, two meters in diameter. By mapping the oculi from the outside (because they are covered by brambles) since the 17th century it has been possible to reconstruct the path of the galleries without descending inside them, as Francesco Contini did: he was the first to draw the Great Trapezium in his General plan of the Villa, published in 1668.
For example, we explored a long subterranean pedestrian corridor that starts from Roccabruna and reaches the Accademia, passing inside the retaining wall of the Accademia Esplanade. We reconstructed its route and discovered that three smaller galleries for carts connected the Accademia, Mimizia and Odeon with the Great Trapezium.
The Great Trapezium was a real subterranean ‘subway’, an incredibly modern solution that hid from sight and hearing the endless traffic of carts that brought supplies to the Villa: food, wine, oil for lamps, various furnishings including the wood used to heat the thermal facilities.
It was a system similar to that of modern cruise ships, where next to the luxurious quarters for passengers there is a network of hidden and parallel service routes.