The Arles Amphitheatre dates back to 90 AD. Inspired by the Colosseum in Rome, the amphitheater was designed to hold over 20,000 people while they watched chariot races and hand-to-hand battles (Wikipedia). In the 5th century, it became a fortress with a small 200 house village inside.
In the early 18th century, the amphitheater returned to its original use as an arena. The houses were removed but the medieval towers remained. Today, it remains in use for bullfights, plays, and concerts.