The current basilica was built in a single campaign by Cardinal Anastasius from 1099 and 1120, during which time it was completely renovated. There was a long-held belief that the old church had been destroyed during the Norman sack of the city under Robert Guiscard in 1084, but no trace of fire damage has been discovered in the lower basilica to date. Because the lower basilica was associated with the imperial opposition pope (“antipope”) Clement III / Wibert of Ravenna, it is possible that the lower basilica was filled in and the new church was constructed on top of the existing structure.
Today, it is considered to be one of the most ornately decorated churches in all of Rome. The ceremonial entrance (a side entrance is most commonly used nowadays) is through an atrium (B on the plan), which is now utilized as a cloister, with conventual buildings surrounding it. The spartan facade by Carlo Stefano Fontana (nephew of Carlo Fontana), supported on antique columns, and his small campanile are situated in front of the atrium on either side.
The basilica church behind it is split into three naves by arcades, which are supported by old marble or granite columns and have Cosmatesque inlaid paving throughout. The marble pieces from the old basilica are used in the construction of the 12th-century schola cantorum (E on plan). Behind it, in the presbytery, is a ciborium (H on plan), which is elevated on four gray-violet columns over the shrine of St. Clement, which is located in the crypt beneath. The bishop seat is located in the apse, which is decorated with mosaics on the theme of the Triumph of the Cross that are considered to be the pinnacle of Roman mosaic art from the 12th century.
The Basilica of San Clemente and the adjacent building complex have been in the possession of the Irish Dominicans since 1667. As a result of their ordeal, Pope Urban VIII granted them asylum in San Clemente, where they have since remained, running a house for priests studying and teaching in Rome. It was the Dominicans that carried out the excavations themselves in the 1950s, working in partnership with Italian archeology students.