Colosseum, Rome

Completed in 80 AD under Emperor Titus, the Colosseum could seat 50,000 to 80,000 spectators and featured a retractable awning (velarium) operated by naval sailors to shade the crowd. It had 80 entrances for crowd flow, numbered seating, and a hypogeum (underground) system of lifts and trapdoors for surprising the crowd with wild animals and stage effects. It was the most advanced entertainment venue of the ancient world.