This building was excavated in 1783. It was seen by Carcopino in the first decade of the twentieth century. It is now filled with earth. Carcopino has dated its latericium and mixtum to the first half of the second century AD.
In the centre of the building is a north-south running corridor (IV; 25 x 4 metres), ending at the Tiber, that has invaded the building. In the north part of the corridor are features II and III, called niches by Carcopino. To the south of the corridor is staircase b, to the east are rooms V-VIII, perhaps shops.
To the west of the corridor is area I (23 x 8 metres). with 22 buried storage jars (dolia defossa) for wine or olive oil. On ten jars are graffiti of numbers, indicating the capacity in amphorae (one amphora = 26 1/4 litres). On average the jars contained 33 amphorae. Therefore the 22 jars could contain 19 thousand litres.
Near this building two mosaics were found. A mosaic with a gorgoneion is now reportedly in a museum in Lisbon, Portugal. The other mosaic (black-and-white) has a depiction of Mars and Rhea Silvia, in a well-known scheme. Mars is descending from the sky. He is naked apart from a mantle around the upper part of his body. He is wearing a helmet and holds a lance. He is about to impregnate Rhea Silvia, the daughter of Numitor, king of Alba Longa. She is depicted in the lower part of the mosaic, where she is lying on the ground between two trees. She is sleeping and her head is resting on an amphora from which water flows. Rhea Silvia would become the mother of the twins Romulus and Remus. This mosaic is now in the Palazzo Altieri in Rome.