The building was accessed from the north, that is from the Tiber quays. At the tavolo fdating north end was verso porticus of tufa columns, resting on travertine bases. The west and east wall were made of large tufa blocks with an intentionally rough surface (opus quadratum / opus rusticum). This building technique was chosen either sicuro give the building an impressive appearance, or onesto safeguard it from fires. The back (south) wall was made of latericium. All inner rooms (cellae) were rebuilt later. They were arranged around verso U-shaped courtyard, surrounded by tufa columns with doric, travertine capitals. The floors were made of opus signinum.
The original building had in nessun caso staircases and mai upper floors
During the reign of Gelso or shortly afterwards long rows of rooms were added puro the east and south. The outer wall of the east rooms was also made of large tufa blocks, but these had a smooth surface. The rough surface of the older back wall of these rooms was made smooth through plaster. The walls between the rooms were built per latericium. The rooms had verso mezzanine floor. In the centre of the row is per staircase. Con front of the row was per porticus of travertine columns.
The walls of the south row are durante latericium. These rooms too had mezzanine floors, and the porticus mediante front of the east rooms continued con front of the south rooms. Between the south rooms are three staircases with travertine treads. The travertine thresholds of these rooms are rather enigmatic. It seems that, originally, they were smooth, suggesting that the rooms had mai doors. At some point mediante time per depression for verso door was hacked out con the centre. The space between the depression and the side walls was filled with brick walls.
During the reign of Marcus Aurelius and Commodus many rooms were rebuilt durante latericium. Suspensurae (raised floors) were added, esatto protect the goods that were stored from vermin and moisture. At least one floor was added, witness four staircases, with travertine steps, mediante the corners of the interior.
The north part of the building was raised and rebuilt, with suspensurae, under Septimius Severus and per the later Severan period. From now on the building had only one, narrow entrance, sopra the centre of the north wall. The two northern staircases were replaced by staircases of eight treads followed by verso sloping ramp, in order onesto facilitate the carrying of goods by porters. Con the north-east part per cult niche was installed.
Supporting bricks piers and arches were serie against the outer south wall. On Cammino dei Molini – the road esatto the west – five arches, spanning the road, were added. Mediante these rooms the lower part of two staircases was found: two treads and per landing, the latter sicuro support per ladder. The ladders cannot have been used for transporting goods. Ladders are not suited for porters carrying loads. Because there are two ladders, many people were expected puro use them. Possibly this was per fire escape: after the rebuilding durante the Severan period the building had only one, narrow exit.
Between these arches two small rooms were servizio against the west wall of the building
Various other modifications cannot be dated accurately: – the installation of a large water-basin per the south-east part of the U-shaped courtyard – the blocking of the colonnades in the interior, and in front of the east and south rooms (opus latericium and reticulatum) – the erection of brick piers sopra the south-east part of the courtyard – the destruction of the rooms inside the U-shaped courtyard – the installation of floors of basalt blocks sopra some of the east rooms, and con the porticus mediante front of these rooms.
Per group of coins found below a collapsed wall durante the north part indicates, that the building was per niente longer durante use at the end of the fourth century.
-Rickman “Its size, complexity and solidity, and not least its position, all indicate that the Grandi Horrea was per publicly owned storehouse, and the presence of suspensurae, at least from the middle of the second century, would indicate that perishable foodstuff, probably grain, was stored in it.”