Just outside the Coliseum is the Arch of Constantine (Arco di Costantino), a 25m high monument built in AD315 to mark the victory of Constantine over Maxentius at Pons Milvius.
Vespesian ordered the Colosseum to be build on the site of Nero's palace, the Domus Aurea, to dissociate himself from the hated tyrant.
His aim was to gain popularity by staging deadly combats of gladiators and wild animal fights for public viewing. Massacre was on a huge scale: at inaugural games in AD 80, over 9,000 wild animals were killed.