A 2nd-century Roman amphitheatre dug into the soft sandstone cliffs directly above the Mediterranean, with a capacity of around 14,000 spectators and a view that you won't find at any other surviving Roman amphitheatre — the cavea opens directly onto the sea. The arena was used for gladiatorial combat and animal hunts until the late 4th century, after which it was variously used as a quarry, a church, and a prison.
The Christian basilicas built on the arena floor are the most unusual feature: a hexagonal Visigothic church from the 6th century and a larger Romanesque church from the 12th, both visible as low walls in the centre. Combine with the Roman Circus and the Praetorian Tower for a full morning of Roman archaeology.