Mausoleum of Honorius

[1] Its association with the medieval Kingdom of France continued until the Renaissance, and it was known by the Italian: Capella dei Re Franchi, lit.

[1] Under the arch of each of the mausoleum's seven niches, a vaulted brick chamber (sacellum) existed some 2 metres (6.6 ft) beneath the floor, within which the sarcophagi would have been laid.

[1] However, it is possible that the brick chambers were not part of the original plan, and that the imperial sarcophagi were vaulted over with a higher floor at a later period.

[a][3] Theodosius, the first son of the augusta Galla Placidia by her first husband Athaulf, king of the Visigoths, was recorded by Prosper of Aquitaine as buried there in 450.

[10] Honorius's brother Arcadius, augustus in the east, was buried in the "South Stoa" of the Church of the Holy Apostles.

[3]For the construction of the 16th-century St Peter's Basilica, the 4th-century Constantinian building was gradually demolished, together with all its chapels, by order of Pope Julius II.

The Mausoleum of Honorius (S. Petronilla) and the Vatican Rotunda were demolished to make way for the far larger ground-plan of the Renaissance basilica.

[1] The building has never been the subject of archaeological excavation, though surviving parts of it may remain beneath the south transept of St Peter's Basilica.

The building's floor plan is known from a drawing in the 16th-century codex known as the Anonimo Fiorentino in the National Central Library of Florence, which also shows the adjoining Vatican Rotunda[1] The plan suggests the Mausoleum was extremely similar to the Vatican Rotunda, though the Renaissance artist may have "regularized" the design.

[1] Niccola della Tuccia's Chronicle records that in June 1458, while a grave was being dug in the Chapel of St Petronilla, a sarcophagus was uncovered "of very beautiful marble".

Besides "an inscribed cross", no identifying features were discovered; nonetheless, the chronicler wrote that "it is said that they were the bodies of Constantine and one of his young sons".

[1] This boy, the first child of Placidia from her first marriage to Athaulf, died young and was initially interred in a church in Barcelona in a silver casket (according to Olympiodorus of Thebes) before being permanently buried in the Mausoleum of Honorius.

[d][1] Marcantonio Michiel's diary contains a report on another exhumation during the demolition of the mausoleum in late November 1519.