A 17th-century Roman masterpiece has been restored to its original splendor. The dome of the Clementine Chapel, located inside St. Peter's Basilica, has been fully restored. The mosaics spanned 371 square meters and were made between 1601 and 1604 using preparatory sketches by Cristofano Roncalli, also known as Pomarancio. Restoration started in May 2025. The Chapel is named after Pope Clement VIII (Ippolito Aldobrandini), who commissioned its elaborate decorations. Originally designed by Michelangelo Buonarroti and finished in 1580 by Giacomo della Porta as a symmetrical companion to the Gregorian Chapel, the work is part of the complex of spaces surrounding the Confession of St. Peter. The mosaics were created by a team of more than ten great mosaicists, including Marcello Provenzale, Paolo Rossetti, and Ranuccio Semprevivo. Before beginning the manual restoration operations, a diagnostic campaign was carried out, including high-resolution photographic recording, laboratory examination of materials, digital mapping of the deterioration, and endoscopic investigations. The complete project management was carried out using the Building Information Modeling (BIM) technique. All survey data, mapping, and work details were integrated with the dome's 3D model, resulting in a digital repository designed to guide future care.