The Mithraeum of the Seven Gates (7.05 x 5.80) was built in a store room in the south-east corner of a warehouse from the first century AD (IV,V,12). The installation took place in the years c. 160-170 AD. See the Mithraeum of the Seven Spheres (II,VIII,6) for Roger Beck's interpretation: he maintains that the mosaics are a reference to a Saturn-Jupiter conjunction that took place in 173 AD.

The shrine is entered through a door two meters wide, with a travertine threshold with pivot holes for two doors opening inwards. Brick podia were set against the lateral walls, and a floor mosaic and paintings were added. The podia were reached along a few brick treads at the front. Inside the podia coins were found of Hadrianus with a depiction of Roma seated on weapons, and of Antoninius Pius with a depiction of a standing figure holding a patera and a sceptre. In the vertical side of the podia, halfway down the shrine, are rectangular niches. In both a small, rectangular, marble altar was found. In the niche on the right side a terracotta vessel had been buried, in which bones were found of poultry and perhaps rabbits, plus three small, broken, ovoid vessels.

At a distance of 1.80 from the back wall is a round terracotta vessel in the floor, 0.25 deep. On either side is a small, square, marble slab. The slabs are both pierced by a lead water-pipe. At 0.40 from the back wall is a square masonry altar (0.45 x 0.50, top missing), decorated with white plaster. A semicircular or round, horizontal hole passed through the entire altar. It was closed off by glass, of which fragments were found. Behind the glass was probably a lamp. The altar rests on a marble column base, below which a second-century coin was found of Faustina the Younger (wife of Marcus Aurelius), with a depiction of a seated Ceres holding grain ears. Nearby a terracotta lamp for six wicks was found.

Behind the altar, in the back wall, is a large, square, arched wall-niche (starting at h. 1.40, w. 1.50, h. 0.80, d. 0.30). It was painted blue with red spots. The central part of the back wall of the shrine was painted red, the colour of the sun and fire. Above the podia is a garden painting, with palm trees. The garden is a symbol of rebirth.

Between the podia is a black-and-white mosaic. Behind the threshold is a central gate flanked by columns supporting an arch with battlements or pinnacles. An object is hanging down from the arch. On either side are three minor gates, separated by columns, with battlements. The seven gates are a reference to the seven planetary spheres through which the souls of the initiates passed. The seventh gate is made of gold and belongs to Sol.

There are also mosaic depictions on the vertical side of the podia. On small pilasters near the door, badly preserved, must have been mosaic depictions of Cautes and Cautopates, the former with a cock and a raised torch, the latter with a lowered torch, symbols of, respectively, the morning and evening. Four planets are depicted on the podia. On the front part of the right podium is Mars with a helmet, a lance in his right hand, and a trophee with cuirass resting on his left shoulder. Further on is Luna, a naked woman with a moon crescent on her head. On the front part of the left podium is Venus Anadiomene ("rising from the sea"). In the centre is a naked Mercurius, with purse and caduceus. Also on the vertical side and on the horizontal rim of the podia are floral motifs.

Two more planets are depicted on the floor. In the back part is a standing, bearded Jupiter, with a bolt of lightning and a sceptre. Near the back wall a bearded bust with a pruning knife represents Saturnus. The seventh planet, Sol, was represented by Mithras who must have been depicted in the niche.

In front of Jupiter we see a krater, symbol of the water in the cave of Mithras, a snake emerging from a rock, symbol of the earth, and a bird, probably an eagle, symbol of the air. The object in front of the eagle is probably a bolt of lightning, symbol of the fire.

The following objects were found:
- Fragments of a krater with a glazed surface, imitating metal. Figures were depicted on the krater. Preserved are Minerva with lance and shield, a figure holding a lance (possibly Jupiter, in which case Juno may also have been depicted), Dionysus-Bacchus with thyrsus and kantharos, and Hercules with a club and a vessel. Probably the twelve gods were depicted (dodekatheon).
- The lower part of a statuette of Cautes or Cautopates.
- A small marble altar with inscription: