The Circus of Carthage was one of the great chariot-racing tracks of the Roman world — close to 500 metres long and 80 wide, with seating for around 45,000 spectators. It sat on the western side of the imperial city, parallel to the amphitheatre. Almost nothing of the structure survives above ground: the stone was robbed out during late antiquity and the Middle Ages, and the modern road network has been laid across part of the original site.
What you can see today is essentially the outline of the track — a long depression in the open ground between the modern residential streets, with a few stretches of stone foundations marking the lower seating tiers. Aerial photography shows the shape very clearly. There is no entry fee and no real signage; visit together with the amphitheatre just to the north for a sense of the scale of the entertainment infrastructure of imperial Carthage.