The Albano cistern is not only important for its size (it can store over 10.000 cubic meters) but also because it is still working today. In fact, it was reused from 1884 to 1912 as a potable water reserve and later used to water gardens and parks. The ground plan is an imperfect rectangle, with the long sides measuring 47.90 m. and 45.50 m. and the short sides measuring 29.62 m. and 31.90 m. It is divided into five aisles with vaulted roofs that are supported by 36 pillars and is coated with hydraulic cement rendering the walls waterproof (opus signimun). Part of the cistern was hollowed out of the rocky bank and the rest was built in masonry.