Regio III Isis et Serapis

Regio III took its name from the double sanctuary of Isis and Serapis, in the area of the Via Praenestina, containing the valley that was to be the future site of the Colosseum, and parts of the Oppian and Esquiline hills.

Centred on the Oppian Hill, Regio III was bordered to its south east by the Via Tusculana, to the north by the Clivus Suburanus, and to the west by the Via Labicana.

The most important ancient festival held there was the Secular games hosted by the Roman emperor Philip in 248 CE, celebrating the 1000 year anniversary of the foundation of Rome.

Also destroyed (though the foundations are still visible) is the Ludus Magnus (also known as the Great Gladiatorial Training School), the largest of the four gladiator training schools (ludi) in Ancient Rome built by the emperor Domitian, as well as the Ludus Dacicus, sited on the lower northern slopes of the Caelian Hill.

Here, marines specially enlisted from the Roman naval headquarters at Misenum were housed and were employed to work the velarium at the Colosseum.