Each Roman church that was affected by building work in the High Middle Ages is presented monographically, focusing on its architectural and liturgical elements that were erected in the 11th–13th centuries. This includes portals, wall tabernacles, the schola cantorum, ciboria, ambos, thrones, Easter candelabra, tombs and the opulent opus sectile pavements that were often connected with the so called Cosmati (named after Cosmas, a stonemason, who signed proudly his works). The aim is not a new art history of the Roman Middle Ages according to developmental aspects based on its sacred buildings, but rather an inventory and overview of the interior topography of Rome's medieval churches, which has been largely destroyed since the end of the 16th century. Nonetheless, the systematic analysis of the churches concerned in individual chapters represents an important contribution to the history of the sacred topography of the city of Rome in the Middle Ages. On the base of the individual churches, further information can be gained about the social groups that were involved in their construction and use, which were by no means only the Pope and the Curia: each individual building has its position in the conflict between the politically influental parties at that time and served to represent the Curia, the nobility, the Senate, the municipality or religious orders in a society in which signs and visible distinctions were important. By also reflecting on the reception and restoration of the churches right up to the present day, these "building biographies" are part of our own history of ideas and intellectual history.