San Clemente is about a 5 minute walk from the Colosseum and deserves the description I got from my guidebook- the lasagna of churches. There are 3 layers to the church, the lowest (and oldest) being a Mithraeum.

San Clemente is an excellent example of the rich history of Rome, from pagan to Christianity. Definitely not one to miss!

Full of interesting aspects and well worth the 5 minute walk from the Colosseum to see them.The colours in the Basilica are deep and glorious.Particularly so in the case of the 12th century mosaic (mainly deep blue)in the apse-This was the only photo of a mosaic which I took on my trip,so I must have been absolutely impressed.
Admission to the earlier church is via the room to the right in the Church,the charge is now 5 Euro.
Downstairs are the 11th century frescoes as well as badly deteriorated ones, which are going to be renovated with donations from the charitable clergy of Ireland.
There are also impressive marble columns and an open, side chapel.The Normans had destroyed much of the church in the 11th century-those chaps certainly liked to travel...
Further back, are steps leading down to the temple of Mithras (a single room,which you can't enter)and quite a few Roman era rooms,some with 'herring bone'floors.There's also running water passing through a Roman drain.
This is all so fascinating and brings history -with all its dimensions- to life, for me; as all this information is under one roof (or several,depending how you look at it)....

Of all the antiquity sites you can visit in Rome (and there are so many it'll make your head spin), San Clemente is a perfect example of what Rome is all about. A 12th century basilica built on top of a 4th century one, which was built over a roman house and mithrian shrine. You enter via the 12th century church, which in itself is pretty spectacular, and for 3 euros you then gain access to the excavations below ground. Some wonderful frescoes which are still in the process of being restored and preserved. But I was blown away by the ancient shrine to Mithras, which was well preserved and very atmospheric.

It is not far from the Colosseum, so is a must-see and easy to get to.

Absolutely essential on any visit to Rome. The Mithraen Temple is extraordinary and the Church quite beautiful. Everyone should see this!