The domed, circular Mausoleum of Santa Costanza, constructed in Rome around 350 to house the remains of one of Constantine’s daughters, is an early example of the centralized sanctuary type of ecclesiastical architecture.

An alternative to the longitudinal basilica, the more diverse centralized type, which could be built to a circular, polygonal, square, or Greek-cross plan, could serve as a baptistery, a memorial, a martyrium, a mausoleum, or as a congregational church.

Extensive mosaics decorate the ambulatory vaults of the Mausoleum of Santa Costanza with geometric and figurative patterns.

Among these are a magnificent version of the popular Hellenistic motif called the "unswept floor"—a scattering of shells, bowls, pitchers, branches, and birds that might have covered a floor after a feast.

The mausoleum’s dome is adorned with Old and New Testament scenes (now lost).