In 1954 excavations revealed a building identified as a temple because of the large number of religious sculptures that were found there. The temple was built in about AD240 and with various alterations it remained in use as a Mithraeum for over 100 years until about AD350 when the temple structure suffered severe subsidence and the building became dilapidated with large cracks in the walls, probably due to the fact that the followers could no longer afford its upkeep.
The stone temple was built to resemble a low cave-like building with a sunken floor in the central nave and aisles separated from the nave by columns. It was rectangular (about 18 x 8m) with a semi-circular apse at the western end which would have housed the statue of the cult god, a full-size figural scene that depicted Mithras slaying the bull - the central belief that everlasting life sprang from the blood spilt during ritual killing of the bull. See a larger plan of the temple.
The temple, re-built and dedicated to the god Bacchus, continued in use until the end of the Roman period. A group of marble sculptures were buried in a small pit under the floor of the nave out of respect for an older religion. These sculptures included the heads of Mithras, Serapis and Minerva, the hand of Mithras and the figure of Mercury. The sculptures of deities Serapis, Mercury and Minerva, although belonging to religions different to that of Mithras, performed some function or had become identified with some part of the worship of Mithras. These sculptures are now on display in the Roman London Gallery of the Museum of London.
For further information about the temple, see Mithras in Religious life.