This unusual group of more than 30 metres of underground galleries used to belong to a system of water conduits designed by Roman engineers in the 1C AD. Discovered in 1963, excavation did not start until 1991. It contains a system of Roman drains with a main gallery with a barrel vault and a floor covered in original terra-cotta tiles were water from other galleries must have flowed to. A group of cryptoporticos was rebuilt on the same site.