The building was accessed from the north, that is from the Tiber quays. At the north end was per 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 esatto 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 niente affatto staircases and mai upper floors
During the reign of Gelso or shortly afterwards long rows of rooms were added esatto 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 in latericium. The rooms had a mezzanine floor. Sopra the centre of the row is a staircase. Per front of the row was per porticus of travertine columns.
The walls of the south row are sopra latericium. These rooms too had mezzanine floors, and the porticus durante front of the east rooms continued in 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 per time a depression for verso door was hacked out in 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 mediante latericium. Suspensurae (raised floors) were added, puro protect the goods that were stored from vermin and moisture. At least one floor was added, witness tagliandi parship four staircases, with travertine steps, in the corners of the interior.
The north part of the building was raised and rebuilt, with suspensurae, under Septimius Severus and in 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 per sloping ramp, con order onesto facilitate the carrying of goods by porters. Sopra the north-east part per cult niche was installed.
Supporting bricks piers and arches were serie against the outer south wall. On Coraggio dei Molini – the road sicuro the west – five arches, spanning the road, were added. In these rooms the lower part of two staircases was found: two treads and per landing, the latter to support a 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 a fire escape: after the rebuilding durante the Severan period the building had only one, narrow exit.
Between these arches two small rooms were set against the west wall of the building
Various other modifications cannot be dated accurately: – the installation of per large water-basin con the south-east part of the U-shaped courtyard – the blocking of the colonnades per the interior, and mediante 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 con some of the east rooms, and in the porticus con front of these rooms.
Per group of coins found below a collapsed wall con the north part indicates, that the building was no longer sopra 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 a 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 sopra it.”