The outstanding feature of Maxentius’ enormous 4th-century palace complex is the Circo di Massenzio , Rome’s best-preserved ancient racetrack – you can still make out the starting stalls used for chariot races. The 10,000-seat arena was built by Maxentius around 309, but he died before ever seeing a race here.
Above the arena are the ruins of Maxentius’ imperial residence, most of which are covered by weeds. Near the racetrack, the Mausoleo di Romolo (also known as the Tombo di Romolo) was built by Maxentius for his son Romulus. The huge mausoleum was originally crowned with a large dome and surrounded by an imposing colonnade, in part still visible.