What Roman amphitheater could hold up to 50,000 spectators?

What Roman amphitheater could hold up to 50,000 spectators? The Colosseum.

The Colosseum in Rome, also called the Flavian Amphitheatre, could hold an estimated 50,000 spectators. Ancient sources give higher figures, but modern estimates commonly place its capacity around 50,000 to 65,000, depending on seating arrangements and the period considered.

Construction began under Emperor Vespasian around AD 72 and was completed by his son Titus in AD 80. Later modifications were made under Domitian. The enormous elliptical arena hosted gladiatorial contests, animal hunts, executions, public spectacles and staged events. Its tiered seating reflected Roman social hierarchy, with the emperor and senators receiving the best views.

The building was engineered for rapid crowd movement: 80 ground-level entrances helped spectators reach assigned sections, and passageways known as vomitoria allowed large crowds to enter and leave efficiently. The Colosseum is sometimes confused with the Circus Maximus, a much larger chariot-racing venue, but the Circus Maximus was a circus rather than an amphitheater.