Rome, S Martino ai Monti
|Also known as
|SS Sylvester and Martin
|Viale del Monte Oppio, 28, 00184 Roma RM, Italy
The original church was fourth century, but there have been several rebuildings including in the ninth, and the current form is largely thanks to the eighteenth century work.
But the small fragments of mosaic that survive are below the church in the ruins of a large Roman building on which the church is built. They are said to be third century. I need to go back and check them over - I think there we bits of a ?bishop, but I have forgotten. To get in, there's a door to the left of thre altar area; you may need to get the key from the sacristan.