The Mithraeum of the Foot-sole was installed in a Hadrianic hall consisting of rows of brick and tufa piers. The shrine seems to have had three naves. In the room to the east of the shrine are some basins and a well. In the west wall of this room is the main entrance of the shrine, on the east side of the central nave (w. 0.80). Two doors connect the central and the left nave. The western door is blocked by a low bench (see below). A few treads lead from the central nave to the back part of the right nave, a small room with a curved niche in the west wall.
Walls of opus vittatum were built between the piers on the right side of the central nave. Small benches, 0.40 high and 0.25 deep, were set against this wall and against the piers on the left side. There are no traces of podia. There could have been a podium in the left nave, but not in the right one, in view of the height of the vittatum walls, that would have been in front of the podium. In the central part of the vertical side of the low benches are small niches (w. 0.42, h. 0.35, d. 0.30 and 0.60). In the niche on the right side chicken-bones were found.
In the back of the shrine is a large, irregular niche of small tufa stones (d. 2.00). It is decorated with plaster, with a yellow background. In the niche is a stepped altar. On the first level is a geometric black-and-white mosaic. The second level is decorated with marble. In the centre of the third level, set against the back wall, is a masonry base. In front of the niche a travertine and a marble base are standing against the lateral walls (0.30 x 0.32, h. 0.60, and 0.30 x 0.27, h. 0.50). They probably carried statuettes of Cautes and Cautopates.
Between the low benches is a simple black-and-white mosaic, with a few yellow and pink tesserae. It is divided in two equal compartments by black bands. In the part near the entrance are two depictions: a snake (1.00) and the imprint of a foot (0.25). Below the mosaic is an older floor, also with the imprint of a foot, in brick. This is the foot of Mithras, on which the initiates placed their own feet. Foot-imprints are also documented in the cult of Serapis. The Ostian Serapeum is close to this Mithraeum. Another connection between Mithras and Serapis is their association with Sol, and in the masonry of the altar in the niche a coin was found of Valerianus (253 - 259 AD), with a bust of Sol on the reverse.
In the altar the following inscription was reused:
The following objects were found:
It may be significant that in the nearby Serapeum an inscription from 200 AD mentions a son of M. Umbilius Maximus, in 192 AD patronus of the corpus lenunculariorum tabulariorum auxiliariorum Ostiensium.
The shrine was built in the second half of the second or the early third century AD. Modifications have been dated to the second half of the third century.
Plan of the caseggiato. After SO I.
Plan of the mithraeum. North is to the right.
SO II, fig. 18.