Piscina Mirabilis
About
Carved into volcanic tuff above Misenum, the Piscina Mirabilis held up to 12,600 cubic meters of fresh water under a vaulted roof on 48 cross-shaped pillars in five aisles. Augustus had it built between 33 and 12 BCE as the final reservoir of the Aqua Augusta, giving the navy's fleet at Misenum water for its base and ships. Sailors nicknamed it the water cathedral, and by 117 CE it had supplied the fleet for over a century. It remains one of Rome's largest cisterns.
What happened here
Underground, vaulted, and much larger inside than anything visible above suggests. The walls are lined with waterproof mortar, the corners rounded so nothing can lodge, and the roof carried on rows of piers. Water arrives by aqueduct or off the roofs and is held against the dry months, for a fleet, a bath house, a fort or a whole town. Sediment settles in a trap before the main tank, and the tank is drained and scrubbed on a cycle by men who go down by ladder. Access is through shafts with stairs, and it is cool enough down there that things are stored in them. A town on a dry site lives or dies by its cisterns, and they are among the first things built.
Sources
Roman Maps shows the empire frozen at 11 August 117 CE, the day Trajan died — its moment of greatest territorial extent. Explore the full map →