The
Castellum aquæ is a large
water reservoir linked to the Serino
aqueduct. It is located in the highest point of the city near the Vesuvius
Gate.
It is covered with bricks and on its façade
there are three blind arches separated by pilasters. The side entrance
of the building was closed by a massive door. The inside of the
reservoir is divided into three sections: one for the fountains,
one for public buildings and
one for private houses. In
case of a water shortage, the less important water supplies were
automatically cut off. The building appears in the relief of Cæcilius
Jucundus which potrayed scenes of the earthquake of 62 A.D..