This amphitheatre takes its name from the word "castrum" which was used in ancient Rome to designate the imperial residences. This Imperial villa was started by Septimius Severus and finished by Helagabalus, the Emperor who so loved circus games and gladiator clashes that he built a circus and an amphitheatre in his villa.

This smaller version of the Colosseum was reserved only for the Emperor and his guests. It was oval in shape and constructed in brick. There were 3 rows of arches on the external walls and, on top, the supports for the velarium, or great awning.
It suffered the same fate as many other monuments that were incorporated into the Aurelian Walls, for it became a defensive fortification.