The Colosseum is an elliptical amphitheatre in the centre of the city of Rome, Italy, just east of the Roman Forum. It is the largest ancient amphitheatre ever built, and is still the largest standing amphitheatre in the world, despite its age. Construction began under the Emperor Vespasian in 72 and was completed in AD 80 under his successor and heir, Titus. Further modifications were made during the reign of Domitian. The three emperors who were patrons of the work are known as the Flavian dynasty, and the amphitheatre was named the Flavian Amphitheatre by later classicists and archaeologists for its association with their family name (Flavius).

An amphitheatre or amphitheater is an open-air venue used for entertainment, performances, and sports. The term derives from the ancient Greek ἀμφιθέατρον, from ἀμφί, meaning "on both sides" or "around" and θέατρον, meaning "place for viewing".