The Mithraeum was converted into a church in the 13th century.
At Sutri, in the same rocky hill in which the Roman Theatre has been built,
there is the Madonna del Parto's church. From its structure it becomes clear that
this originally must have been a Mithraeum.
Frothingham in AJA 1889,320ff; Sestieri in BCR 1934, 33ff and fig.; Cumont,
Mithra en Etrurie, 97ff and Tav. XI, I, with fig. 1 (see fig. 182).
The present atrium of the church certainly served for a pronaos in the original
Mithraeum. By it one enters the proper, orientated sanctuary (L. 21.20 Br. 6.70),
which is sparsely illuminated by three windows in the leftside-wall. Two rows of
ten columns, resting on one uninterrupted base, support the vault above the
central aisle (Br. 2.47). The side-aisles however, have flat roofs.
The sanctuary has thus the usual division into a central aisle and two sidebenches,
the constructiou of which are still easily discernable. For there are two
elevations (H. 0.50 Br. 0.30) running along the bases (a, b) of the columns and two
other elevations run along the side-walls. There is nowadays a narrow corridor (Br.
0.75) along side the latter elevations (c, d) and the bases of the columns; but they
certainly formed one whole.
The floor of the central aisle slopes upwards to the choir, broadening considerably
and beginning at the end of the podia. In the back-wall there is a niche with a
fresco of the H. Virgin but which originally must have contained the relief of
Mithras tauroctone. This niche is accessible via three steps. Remarkable is that in
elevation c a square basin is still visible. A brook, running in the immediate
vicinity, supplied it with the required water.