The monumental complex comprises the Basilica of Sant’Agnese fuori le Mura and the Mausoleo di Santa Costanza, the mausoleum built around 350 and meant to receive the bodies of Costantia and her sister Helen, daughters of Constantine. Under the basilica and in the area around it, are the galleries of a vast catacomb, discovered by chance in 1865 and certainly previous to the burial of the Saint, as proven by numerous inscriptions found here. The three-storey cemetery, without frescoes, si divided into four areas. The oldest one is on the left hand side of the basilica and has a niche closed by a huge slab, as in jewish tombs. The fourth area is under the atrium of the constantine church.
The mausoleum di Santa Costanza is one of the most important museums of the late ancient architecture. Is the first example of round building with an ambulatory. The outline of an oval vestibule can still be traced in front of the entrance. The rotunda itself is covered by a dome resting on a drum which is supported on a ring of twinned columns linked by elegant arches. The surrounding barrel-vaulted gallery is still adorned with its original fourth century mosaic. The vault is divided into panels and covered with a variety of motifs against a light background: floral and geometric details, portraits in medallions, vine tendrils entwined with harvest scenes. The mosaics in the side recesses have Christian themes: God handing down the law to Moses and Christ giving the new law to St Peter and St Paul. In the recess opposite the entrance is a copy of Constanza’s sarcophagus, the original being in the Vatican museums. In the 7th century pope Honorius built another basilica upon the tomb of Sant’Agnese: a Christian basilica of byzantine influence as proven by the mosaic in the apse, one of the most beautiful examples of byzantine mosaics in Rome dating back to the first half of the 7th century: St Agnese between pope Symmachus (498-514) and Honorius (625-638), holding a model of the church.
The church of Sant’Agnese fuori le Mura was built in 324, by the order of Costanza, daughter to Emperor Costantino, on top of the ruins of a cemetery and the catacombs that hosted the relics of the Saint. It was rebuilt made by order of Pope Onorio I and later on restored numerous times. It is one of the most integral and eminent examples of an antique christian basilica. The façade hosts a marvellous Renaissance portal, adorned by the emblem of the upcoming Pope Giulio II, and it is surmounted by a mullioned window. A large marble stairway dated 1590 descends to the narthex of the church. On the walls one finds tombstones’ fragments and architectural elements coming from the catacombs. The interior, preceded by the narthex, embodies three naves separated by fourteen antique columns, with beautiful Corinthian capitals. Very interesting is the mosaic portraying Sant’Agnese as byzantine empress on a golden background, one of the highest examples of byzantine art in Rome. Every year, on the 21st of January, inside the church two lambs are blessed and their wool is used to wrap up a “pallium” the Pope then gives to the newly nominated archi-bishops.
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