Ostia is the oldest Roman colony, at the mouth of the river which served for centuries as the port of Rome. The excavations in the XIX and XX centuries have allowed for the urban and architectural layout of Ostia to be read in its entirety, giving a thorough picture of both the appearance and the function of every building.

Prudent and careful exploration at the beginning of the 1900s made progress, thanks to an exponential increase in means, and based upon a cultural policy committed to obeying the imperialistic dreams of fascism. It was known as the "grand excavation". In anticipation of the Universal Expo in Rome, which should have taken place in 1942, Ostia Antica was intended to be the archaeological fulcrum.

Today tourists can visit the buildings inside and out: numerous temples, theater, painted houses, rich decorations on public buildings, warehouses and stores, sites of worship for the leading religions of the ancient works.