The Fabbrica di San Pietro restored several mosaics in the side chapel dome, a project that began in May 2025.

St. Peter’s Basilica, which is marking 400 years since its consecration, has completed a mosaic restoration in the dome of one of its most ornate chapels.

The Fabbrica di San Pietro — the Vatican institution responsible for maintaining St. Peter’s — announced the project’s completion on Sept. 17. The announcement described the project as necessary to conserve “one of the most significant decorative achievements of early seventeenth-century Rome.” The Italian Mannerist painter Cristofano Roncalli (also known as “Il Pomarancio”) created the mosaics between 1601 and 1604.

The Clementine Chapel, distinct from another of the same name in the Vatican Grottoes, contains the Altar of St. Gregory the Great (where he is buried), the monument to Pope Pius VII, the Altar of the Lie, and the Altar of the Transfiguration.

The restoration included preliminary inspections of the mosaics, cleaning and dust removal, removal of incompatible materials, and efflorescence treatment.

The Clementine Chapel was commissioned by Pope Clement VIII, who reigned from 1592–1605. It was begun and designed by the renowned Italian artist Michelangelo Buonarroti, who also designed the main dome of St. Peter’s Basilica. The Italian architect Giacomo della Porta completed the chapel’s dome in 1580, 20 years before the jubilee year of 1600.

The mosaics were restored as St. Peter’s Basilica marked the 400th anniversary of its consecration. In February, the Vatican announced that it will open new parts of the basilica — including the full terrace — and roll out a “SmartPass” digital entry system.

The basilica, which replaced an earlier Constantinian basilica, was consecrated by Pope Urban VIII on Nov. 18, 1626.

This article was originally published by EWTN News English.