The apse mosaic in San Clemente Basilica is a thing of wonder.
Mystic figures on a golden background, the portrayal of a whole cosmic vision with unsurpassable artistry. You will contemplate it for long moments, imbibing this vision that is so strange to your everyday world.
Now you will descend to the second level, and marvel at the buried basilica. Then deeper still into the earth, down to the third level and the Roman ruins.
And lastly, on leaving the Basilica, you will find yourself in a private area, where a privileged few can admire ancient pieces from the days of Roman glory.