The early Christian church is dedicated St. Stephen, deacon and martyr. It is located on Caelian Hill, one of the seven legendary hills of Rome.
This church is a rare example that unites two types of plants in its interior: one is circular and the other a Greek cross.
It is also one of the oldest churches in Italy of this kind. It was probably built around the fifth century and ordained for worship by Pope Simplicius at the end of the fifth century.
The interior of the small church is very original and filled with frescoes by Pomarancio and Tempesta, which mostly depict the atrocities inflicted on the Christian martyrs.
One of the chapels contains a seventh-century Byzantine mosaic that depicts two martyrs that were buried in the church.