This seems to have been a storage building. Most of it was open to the sky. Two doorways lead to the street. Over the south-western part was a light roof, supported by a few brick piers. In the eastern part a room was created with two tufa columns in the entrance. Perhaps this was an office.
The oldest masonry is Trajanic (opus mixtum, latericium and reticulatum). An extensive rebuilding took place in the second half of the fourth century (opus vittatum).
Plan of the building. Boersma 1985, fig. 25.