This Trajanic building consists of three wings, to the northwest, southwest and southeast of a very large courtyard. The buildings to the northeast and in the northeast part of the courtyard have been numbered separately.
The wings are identical: in the centre is a podium, that could be reached along a few steps. On either side is a long room, accessible through a threefold entrance. In the south corner of the complex is a latrine with many seats. The complex could be entered from the west corner, and from Via della Foce. Apparently large crowds gathered here. Perhaps certain commercial transactions took place on the podia. We may think of auctions of goods that were stored in the flanking rooms.
Plan of the building. After SO I.