Colosseum or Coliseum (both: kŏləsē´əm), Ital. Colosseo, common name of the Flavian Amphitheater in Rome, near the southeast end of the Forum, between the Palatine and Esquiline hills. Begun by Vespasian, c.AD 75, and completed by his son Titus in AD 80, it is the most imposing of Roman antiquities. The vast four-storied oval is 617 ft (188 m) by 512 ft (156 m), much of which is still standing; it had tier on tier of marble seats accommodating c.45,000 spectators. It encloses an arena measuring 250 ft (76 m) by 151 ft (46 m) where gladiatorial combats were held (see gladiators) until 404. According to tradition, persecuted Christians were thrown there to beasts. The Colosseum has been damaged several times by earthquakes.

See J. Pearson, Arena: The Story of the Colosseum (1974).

Colosseum Ampitheatre in Rome, built ad 72–81 by the Emperor Vespasian. One of the most awe-inspiring examples of ancient Roman architecture, it measures 189 × 156m (620 × 513ft) by 45.7m (150ft) high, and seated c.50,000 people. Citizens of Rome came here to watch gladiatorial contests and, according to tradition, the martyrdom of Christians.

Colosseum the name since medieval times of the Amphitheatrum Flavium, a vast amphitheatre in Rome, begun c.75 ad; the name is Latin, and is the neuter of colosseus ‘gigantic’.