Of the hundreds of churches in Rome, only a few are markedly medieval in appearance. The authors of this volume therefore identify previous stylistic building elements using visual and written sources. Emphasis is placed on the reconstruction of medieval architecture as well as on the magnificent marble and porphyry liturgical interiors decorated with mosaics, including pavements, altars, ciborium, chancel screens, pulpits, and Easter candlesticks. Particular attention is given to the history of church reform since the 11th Century. In this third volume, important churches such as S. Giorgio al Velabro, SS Giovanni e Paolo, S. Giovanni a Porta Latina, S. Gregorio al Celio, and S. Lorenzo in Lucina are presented with an abundance of new information. The largest section is dedicated to the investigation of S. Lorenzo Fuori le Mura, one of the gems of medieval antiquity in Rome. It includes new discoveries on the origins of the Holy Sepulchre and a reinterpretation of its architectural history. German text.