The Seven Halls
Previously believed to be connected to Nero's Domus Aurea, they were later found to be a large cistern supplying the Baths of Trajan. The cisterns were fed by a branch of the Trajanic Aqueduct. Found beneath the complex were the remains of a grotto lined with slabs of marble belonging to the Domus Aurea. In the fourth century CE, a domus was built on top of the complex, likely from a building used to service the tank itself. In the Middle Ages, the northernmost chambers were used as catacombs.
The complex, still quite well preserved, is built into the side of the Oppian Hill, shaped to conform to the terrain. The cisterns comprise nine (not seven) parallel chambers 17.4 feet wide and ranging from 96 to 130 feet long. The name Seven Halls comes from the fact that, when the complex was noted in the mid-eighteenth century, only seven chambers were recognized.
- ROMArcheologica. Guida alle antichità della città eterna, quinto itinerario, Elio de Rosa editore, Roma - ottobre 1999
- Romolo A. Staccioli, Acquedotti, fontane e terme di Roma antica, Newton & Compton Ed., Roma 2005