El Jem. Tunisia. View of a chamber or tunnel directly underneath the arena of magnificent ancient Roman amphitheatre. The underground chambers held animals, gladiators and prisoners before they were lifted up to the arena to suffer their unfortunate fate. Dating from 230-238 AD, the splendid Roman amphitheatre or Colosseum of El Jem is the third largest in the Roman world and is one of the most impressive Roman monuments in Africa. The Colosseum of El Jem is a UNESCO World Heritage Site.