Why is the Colosseum missing one side?

In 2 17 AD, the Colosseum was partially destroyed by lightning, but it recovered quickly in 238, and the fighting performance between people and animals or between people continued. Such activities were not completely banned until 523 AD. Two strong earthquakes in 442 and 508 AD caused serious damage to the Colosseum structure itself.

In the Middle Ages, the buildings were not protected at all, so the damage was further aggravated, and later they were simply used as bunkers. In15th century, the Vatican demolished some stones in the Colosseum in order to build the church and the Privy Council. 1749, the Vatican declared it a holy place and protected it on the grounds that Christians died here in their early years.

The stands of the Colosseum in Rome are supported by three concrete cylindrical arches, with 80 arches on each floor, forming three circular coupon corridors with different heights (that is, corridors supported by arches), and the top floor is a 50-meter-high solid wall.

The stands retreated step by step, forming a stepped slope. 80 arches on each floor form 80 openings, and the top two floors have 80 openings. When the audience enters, they will first find out which bottom arch they should enter according to the number of seats, then find their own area along the stairs and finally find their own seats.

The entire Colosseum can accommodate up to 90,000 people, but due to the thoughtful design of the entrance, there will be no crowding and chaos. This entrance design is still in use even in today's large stadiums.

Baidu Encyclopedia-Colosseum (Italy Colosseum)