Some historians believe its origins could date to the fifth century[2] as it appears to be built on the ruins of a Roman building from the Late Republican period consisting of eight columns and two apses.
At the time, its early Christian character had been completely revamped as a Byzantine church with a plan in the form of a Greek cross.
[1] In 1775 the building was greatly weakened by the removal of three Numidian marble columns for use as flooring in the royal chapel of the Palace of Caserta;[5] other damage occurred in 1928 the priest's house was built, as the front porch was demolished and the facade was altered.
[2] In 1990, renovation work revealed a Roman opus signinum floor and a section of brick wall from the fifth century.
[2] The church of San Costanzo has a very simple façade which dates from the late nineteenth and early twentieth century when the porch and triangular gable were demolished to provide stone for building the priest's house.