The outstanding feature of Maxentius’ enormous 4th-century palace complex is the Circo di Massenzio, Rome’s best-preserved ancient racetrack. Above the arena are the ruins of Maxentius’ imperial residence. Near the racetrack, the Mausoleo di Romolo was built by Maxentius for his 17-year-old son Romulus. Fully seeing the sights here will require a very pleasant and pastoral stroll through the vast site. Panels near the entrance have details on the many wildflowers and plants throughout the area.
Note that the villa itself, which is on a hill behind the Circo, is closed for long-term research; the rest of the site is open.