Since quite a few people are interested, here are some more pictures of the Colloseum at El Djem (historic Thysdrus)
Looking down at the arena
High up in the cheap seats, there were plenty of stairs so it could be filled/emptied quite quickly.
A view over the arena, showing how high the cheap seats are, amazing to think it could hold 35,000 spectators
The more expensive seating , mainly reconstructed.
Down underneath the arena, where the animals and captive were kept, there were two lifts to take them to the surface.
An explanatory board