It is located in the Monti district, between the Esquiline and Celio, on the road which connects the Colosseum to the Lateran.
The basilica was developed on three levels that overlapped in time, in fact, it consists of two different buildings of worship overlapped, under which they develop extensive underground areas where the remains of some Roman buildings of age Imperial and a mithraeum dating from the third century.
One of these buildings was probably the home of Clement, who was martyred under Domitian, whose relics were preserved in the church built in his honor in the fourth century and which is the current lower basilica, an important place of worship throughout the Middle Ages and home to many church councils.
The basilica itself (the upper one) was completed in 1123 by Pope Paschal II after the pre-existing basilica (the lower one) was severely damaged during the sack of the Normans in 1084 and then buried.
From the main entrance of St. Clement you access to a internal courtyard above the bell tower and facade of the eighteenth-century, work, in Baroque style, of Carlo Stefano Fontana.
At the top level there is the upper basilica, one of the most famous medieval churches of Rome.
The interior, with its magnificent floor Cosmatesque preserves its medieval appearance despite several changes of the following centuries as the rich baroque decoration made by Carlo Stefano Fontana. The choir, for example, still presents the marble slabs dating from the twelfth century, partly recovered from the lower basilica.
is divided into three naves, each ended with an apse and divided by ancient columns from various sources. In the central apse is preserved the wonderful mosaic of the Roman school depicting the Mystic Lamb with the twelve sheep and the Triumph of the Cross depicting the crucified Christ between the Virgin and St. John the Evangelist.
Superb example of Renaissance work is Chapel of St. Catherine, where there are beautiful frescoes painted at the end of the second decade of the fifteenth century, attributed to Masolino da Panicale, master of Masaccio, who may have contributed at work. The most important scenes are the Crucifixion and the Stories of St. Catherine.
From the sacristy leads down to the lower basilica which presents a three aisles, divided by columns, preceded by an atrium. Both environment are decorated with frescoes.
The atrium presents mural paintings of the eleventh century depicting theMiracle of St. Clement, the transportation of the body of St. Cyril and St. Cyril in Glory. While the nave is enriched by the fresco "Legend of Sisinnio" the eleventh century. Of the same period are the paintings that adorn the walls of the nave itself.
The lower church, severely damaged during the sack of the Normans, was abandoned and buried to build upon the new basilica. For a staircase, down the aisle on the left, go down to the third level where there are the remains of Roman buildings dating back to the first and second centuries AD and a mithraeum of the third century.