Cistern of the Sanctuary
About
A multi-chambered cistern at the foot of the hillside stored water for the fountains and nymphaea running through the sanctuary's terraces, engineering as ambitious in its own way as the temple above it. Brick-faced concrete construction let Praeneste's builders vault chambers wide enough to hold a real reserve against the dry Italian summer. In 117 CE it still supplies water to a sanctuary drawing pilgrims from across Italy.
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
Nearby
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 →