The "Cross-roads of the Castrum", to the west of the Forum, was one of Ostia's major intersections. On the intersection is a structure that was probably a shrine (compitum). The structure is somewhat below the present street level and may have been built in the first century BC. The main feature is a narrow, rectangular room, built with large tufa blocks with doors in the short sides (inside meas., max. w. 2.37, d. 5.22). Reticulate walls were set against the inside of the lateral walls. That the structure had a religious function is suggested by its position and by the respect shown towards it: the floor level was preserved when the street level was raised.
According to Raissa Calza a small, rectangular cippus, with on three sides depictions of Hercules, Silvanus and Mercurius, was found amongst the ruins (perhaps this is the cippus depicted in Calza-Nash 1959, fig. 90).
Two rooms with a curved outer wall were later set against the west side. One of these was a basin, as is shown by the presence of hydraulic mortar.
3D drawing of the remains, seen from the east.
From Bakker 1994, fig. 18.