The vast square open towards the Tiber was designed together with the theatre in the Augustan period but was equipped with porticoes only during the time of Claudius (mid-1^st century AD).

Towards the end of the 1^st century AD, a temple on a high podium with two Corinthian columns at the front was built at the centre of the square; it was dedicated to a god of uncertain identity.

Details of the mosaics of the stationes

Details of the mosaics of the stationes

Another transformation took place in the first half of the 2^nd century AD, when the portico was doubled and the earliest floor mosaics were laid; the latter were later remade when the internal space was subdivided into different rooms (stationes).

Details of the mosaics of the stationes

Details of the mosaics of the stationes

The motifs depicted were linked to commercial activities; the presence of inscriptions mentioning corporations of traders, ship-owners and entrepreneurs from both Ostia and elsewhere support the theory that these were the headquarters of the corporations themselves.

View of the Piazzale delle Corporazioni laid out as a garden (1913)