The Colosseum, dedicated in 80 AD under Emperor Titus, was a masterpiece of engineering: it could be flooded for mock sea battles, covered to protect spectators from the sun and, thanks to many well-positioned exits, evacuated in a matter of minutes. The interior of this Roman landmark is impressive for its tiered design, the subterranean tunnels and animal cages, and its immense size: the Colosseum could accommodate 50,000 people.