Opposite the Episcopium on the north bank of the Fossa Traiana and further to the east, a large marble yard (statio marmorum) was found. Hundreds of marble blocks and columns were found here and in the Fossa Traiana. Many of these carry inscriptions, made partly in the quarries, partly during an inventory in Portus that took place in 132 AD. The former include the formula ex ratione (cuiusdam) ("from the business of ..."), the latter include numbers and the name of consul Augurinus. From the inscriptions can be deduced that the yard was under Imperial control. It was a stock, from which objects were shipped to Rome. A marble workshop was present, specialised in repairing damaged or faulty objects. If the attempt was not successful, the object was rejected and dumped. The rejected objects have been found. The yard at Portus replaced a yard at the river-harbour in Rome, after the completion of Trajan's harbour. A Tiber ferry at Ostia (where there was no bridge) was in antiquity named after the yard.
Objects from the marble yard to the south of the Fossa Traiana are now on display in Ostia, near the museum. Below are some photographs of the objects, made by Eric Taylor.