The "Mitreo della Casa di Diana". More information is available at the Ostia Antica site.
A Mithraeum, built in the Casa di Diana (Reg. I, Is. HI, 3). The house is early
Antonine (± 140 A.D.).
G. Calza in NSc (S.5) XII, 1915, 324ff and fig.; Becatti, Mitrei Ostia, 9ff
with fig. 1 and Pl. I. See fig. 68.
The sanctuary has been constructed in two rooms, situated in the N. E. corner
of the house. These rooms have cross-vaults and the floors were originally covered
with mosaic. From room A one entered room B through a door on the right, while,
moreover, in the middle of the partition-wall a window had been made. It is not
clear to what purpose the inhabitants of the house had used these rooms, but when
they were altered for a Mithraeum, many changes were introduced to meet the
stereotyped division into central aisle and side-benches. The window in the partition
wall was constructed into a passage (Br. 1.16) and the former door could now be
used to pass from the r. bench of room A to that of room B. The l. bench however,
was divided in two by a remnant of the wall.
In room A (L. 3.74 Br. 6.10) in the central aisle (Br. 1.60) there was a small round basin a (D. 0.15 diam. 0.33) to the right of the entrance (Br. 1.05). The benches in this room are no longer there, but one can see that the r. bench was longer and wider (L. 3.74 Br. 2.30) than the l. bench (L. 2045 Br. 1.90). They consisted mainly of brick and sand and were ascended by one step; they slope towards the walls. In room B (L. 3.96 Br. 5.81) the central aisle is larger (Br. 2.55) and here the benches (H. 0.50-0.54 Br. 1.60-1.66) are preserved. There is a small step (Br. 0.40) to ascend them. The central aisle leads towards a raised platform C (H. 1.45 Br. 1.68 D. 0.88), which is covered with white stucco and is ascended on the right-hand side by three steps. The base supports a niche with on either side a bracket for a small column. The cult-image is lost. To the arch of the niche pieces of pumice were attached in order to give the impresssion of a grotto (traces of a blue colour).