Santa Costanza

The Church of Santa Costanza was constructed around 340-345 AD and was initially intended as a burial place for Constantia and Helena, the daughters of Constantine the Great. In its immediate vicinity was the Catacomb of Saint Agnes. Constantia herself likely endowed a large basilica in honor of Saint Agnes, to which her own mausoleum was directly attached. This combination of a basilica and a round mausoleum was not uncommon in Rome in the early 4th century for members of the imperial family. Since cemeteries were forbidden within the city walls, these structures were originally located outside, about three kilometers north of the Aurelian Wall. Whether Constantia and Helena were actually buried here is not certain; the original porphyry sarcophagus is now in the Vatican Museums. Already before the 6th century, the mausoleum was converted into a baptistery, and in 1254, Pope Alexander IV consecrated it as a church. In 1620, it underwent a Baroque transformation, but a restoration in 1938/1939 restored its 4th-century appearance.