Basilica di San Clemente
The upper church at street level has a theologically complex cycle of mosaics in the apse, created in the 12th century in the Byzantine style. The foliage is a symbol of the living church, which has its roots in the Garden of Paradise, and bears a fruit that is the cross on which Christ was crucified. Christ and the Apostles appear in an allegory of the Lamb of God flanked by a flock of 12 lambs. Near the entrance of the church on the left is a Gothic frescoed chapel depicting the life of St Catherine, which includes the wheel on which she was martyred (thus giving name to the firework). Slip down into the 4th-century basilica church through the door on the right for fading frescoes narrating scenes from the life of Saint Clement, the fourth pope. Another staircase leads even further back in time to a 2nd-century AD alleyway. On one side is a pagan temple or mithraeum dedicated to the bull-slaying god Mithras, which was a popular cult with the Roman army. On the other side of the old alley are the remains of an early Christian house, or ‘titulus’, where the first Christians would secretly meet to take Communion before Christianity was legalized in 313. This was no rat hole, however, but one of the few ancient houses with the luxury of running water (still on tap today).