One of the most beautiful and important sanctuaries dedicated to Mithras. Discovered at the end of September 1922 in one of the criptoportici near the Capitol of the Roman City and close to the Church of S. Erasmo in Capitolio. The siting of this speleum in the vico Caserna indicates yet again how the Iranian god was able to penetrate into the very surroundings of the official State-cult. It seems probable that he had already done so at the beginning of the second century A.D.; the Mithraeum itself was not destroyed but filled up with rubbish in order to make it inaccessible. One does not know whether the Christians are to blame for it, in any case they did not construct a church here as a symbol of their victory. The entrance opens on a criptoportici, which served as a vestibulum and has about the same proportions as the adjacent cult-room (H. 322 L. 12.18 Br. 3.50). On either side of the central aisle (Br. 1.54), which was covered with marble, are the benches. A distinction, however, has to be made between the original benches of cement with red stucco (H. 0.45 L. 1.40 Br. 0.37) and the later benches, made up out of various materials and considerably larger (H. 0.85 L. 8.35 Br. 0.90). In the southern bench a rectangular cement water-basin was made (L. 1.28 Br. 0.67 D. 0.55), Whereas in the other there is a well with draining-pipes. Near these basins there is a small rectangular niche (H. 0.32 D. 0.32) in the front of either bench. At the end of the path, where small steps lead to the benches, there is a third bench (H. 0.68 Br. 3.50 D. 1.57) covering the entire breadth of the cult-room and sloping towards the western wall. A small canal (Br. 0.09 D. 0.08) in the front of this bench, disappears into it at the northern wall and is connected with the well E. In the vault there are four oblong holes surrounded by a red band. Both sidewalls and vault are covered with stucco paintings. The vault is decorated with stars with eight points, painted in red and blue on a yellow background. The background of the side walls, which are subdivided into several parts by horizontal and vertical red bands, is also yellow. On the walls were graffiti, only one of which on the left of C. is readable: . . . . . . Modum.