The Decumanus Maximus is the main street in the east half of Ostia. It runs from east to west, starting at the Porta Romana. At the west end is a crossroads, the Bivio del Castrum, where the road branches in two directions. One branch (also called Decumanus Maximus by the excavators) leads to the Porta Marina, to the south-west. The other branch (Via della Foce) leads to the north-west, to the Tiber-mouth.
Along the north side of the eastern half are a number of travertine inscriptions, the so-called Cippi of Caninius. These were erected between 150 and 80 BC by a Praetor called Caninius. The texts inform us that the land between the Tiber and the eastern half of the Decumanus was public property. Probably it was destined for commercial purposes related to the river harbour, such as the storage of goods. All texts are identical:
C(ai) F(ilius) PR(aetor) VRB(anus)
DE SEN(atus) SENT(entia)
"C. Caninius, son of Gaius, Urban Praetor, by decision of the senate, judged this area to be public property". To the south of the Grandi Horrea (regio II, insula IX) is the westernmost inscription. Next to this one another cippus was placed later, indicating that the western stretch of the public area had become private property:
"Private area from here to the Tiber, to the water".
A few wheel-ruts can be seen between the Porta Romana and the theatre, the only wheel-ruts in Ostia. This indicates that further transport of goods in Ostia was done by slaves or pack-animals, not wagons. In the early middle ages (sixth or seventh century) two large wells were built in the middle of the street. They were found in 1909. Both were made of bricks and marble fragments. One is opposite the Baths of Neptune (regio II, insula VI), the other one was found a bit to the east, opposite regio II, insula III. The latter well has now disappeared. In this period the road was obviously no longer used by wagons.