One of the most interesting of all Roman churches. The medieval
interior, with beautiful 12th century mosaics in the apse, a
fine Cosmatesque pavement, and interesting 15th century frescoes
by Masolino in the Chapel of St Catherine in the left aisle,
leads to the evocative crypt beneath. You pass through a much
larger 5th century church, restored in the 8th and 9th centuries,
with frescoes of the Lives of St Clement and St Alexis, and descend
into a Roman Mithraeum, with a sinister sculpture of Mithras
sacrificing a bull. At the lowest level, among the foundations
of a late 1st century house, you are at the level of the Tiber
and can hear the roar of the river.
