The Amphitheatre - built in the C2 for over 50,000 spectators, was the scene for the martyrdom of Christians in C3. Although only the underground rooms & a part of the foundations remain, they bear witness of its grandeur & magnitude.
Gladiators fought to the death, hunters killed wild animals & some made a living by letting themselves be mauled by animals & priding themselves on the resulting scars. When an emperor ordered a persecution of Christians, individuals who refused to forswear their faith were sacrificed to hungry beasts.
For a handful of photos of the island of the Punic Port - Carthage [14 April 2006], as seen from the road [but there is little to see], view:-