This beautiful ancient theater is located in Ostia Antica, a large archaeological site that was once the location of harbor city in ancient Rome. The theater was built along the Decumanus Maximus – the main east-west orientated road. Fragments of an inscription tell us that a first theater was built at the end of the first century BC by Agrippa, the right-hand man of Augustus (founder of the Roman Empire and its first Emperor). It could hold 3000 spectators. It was built together with a large square to the north, the Piazzale delle Corporazioni. The masonry of the present theater has been dated to the late second century AD. In that period the theater was enlarged, and could hold 4000 people. A large inscription from 196 AD tells us that this rebuilding was the work of Septimius Severus and Caracalla. Brick stamps however show that the work had been started by Commodus (176-192 AD). Today, the theater is still in use for summer events. source: http://www.ostia-antica.org/regio2/7/7-2.htm