Franz Cumont kindly drew our attention on several ancient fragments, walled in the wall of the flight of steps in the house at the Via Boncompagni 101 (boarding- house Cosmopolita).
Lanciani, Storia Scavi, III, 200 gives another interesting note about a second Mithraeum, discovered in 1869 near the previous sanctuary in Muti's gardens.
Fragmentum tabulae magnae marmoreae litteris magnis parum bonis saeculi quinti, effossum in monte Quirinali ubi nunc transit via quae dicitur Nazionale.
"Parte inferiore di un fusto di candelabro a guisa di tronco di palma uscente da un nascimento di foglie d'acanto; nel plinto in tre lati la inscrizione" (Lan- ciani in BAM 1875,248).
In the room left to the entrance of the Mithraeum, there is a well, from which water runs through a pipe, which penetrates the wall and empties in a square basin.