Santa Costanza
Santa Costanza is a church in Rome, built under Emperor Constantine I and place of burial ( mausoleum) of his daughters Constantina and Helena. Later, Constantina was venerated as saint, with the Italian name of Costanza, and the church was dedicated to her.

History
The church was built under Constantine, probably by Constantina, next to the cemetery of Sant'Agnese fuori le mura, where Saint Agnes, who allegedly had healed Constantina, was buried. After their deaths, Constantine's daughters Constantina and Helena were buried here . Since Constantina was venerated as saint, the mausoleum was consecrated as a church in 1254 by Pope Alexander IV. After the church was restored in 1620 by Cardinal Fabrizio Veralli, Constantina's magnificent porphyry sarcophagus was moved to the Vatican Museums. The Church was originally a mausoleum.

Location and structure
The existing building that is Santa Costanza rests at the southern flank of the cemetery basilica of Sant'Agnese fuori le mura, not far from the Via Nomentana some three kilometers north of the gates of the Aurelian Walls. The circular building is twenty-nine meters in diameter, with a central circular chamber eleven and a half meters wide, separated from a ring-shaped ambulatory by twelve pairs of radiating columns. Santa Costanza's exterior survives today in its original state except for the loss of its outer ambulatory. What remains of the interior of the building is ornately decorated with marble and tesserae mosaics which hint at a rich patronage of both pagan and early Christian provenance. The twelve pairs of columns which encircle the central chamber are of fine green and red marble, and are colour coordinated to the points of the cross. The ambulatory ceiling is vaulted, and decorated with mosaics which recall classical themes of Bacchic myth and early Christian beliefs. These same mosaics, like much of Santa Costanza have also been interpreted as discussing notions of the after-life.