Colosseum also called the Flavian Amphitheatre, was the largest outdoor theatre of ancient Rome. The Colosseum still ranks among the finest examples of Roman architecture and engineering, even though it survives only as a ruin. It stands near the centre of modern Rome.

Construction of the Colosseum started during the reign of the Emperor Vespasian, who ruled from A.D. 69 to 79. The building was dedicated in A.D. 80. Until 404, the Colosseum was the site of mock naval battles, combat between gladiators, battles between men and wild animals, and other public entertainment. After that date, gladiatorial battles were no longer held, but fights with wild animals continued there until 523. During the Middle Ages, stones from the structure were used to construct new buildings.

The Colosseum has four storeys and is oval in shape. It could seat about 50,000 spectators on marble and wooden benches. The Colosseum is 48 metres high, about 190 metres long, and about 155 metres wide. The arena on the floor of the Colosseum is about 85 metres long and 55 metres wide. A wall about 4.5 metres high separated spectators from the arena.

The Colosseum is made of brick and concrete with stone covering the exterior. The first three storeys consist of arches decorated with half columns. The fourth storey was added later and has plainer decoration. Large brackets in the fourth-storey walls held poles that supported awnings to protect spectators from the sun and rain. The Colosseum had about 80 entrances, two reserved for the emperor.