Michelangelo was commissioned for this work by Pope Pius IV. Tradition has it that 40,000 Christians were martyred during the building works for these baths, and the pope's idea was to consecrate the most monumental part of the ruins to them.
Michelangelo utilized the great central hall and some of the side rooms and succeeded in leaving intact the great sense of grandeur that the ancient building possessed without imposing his own architecture on the building.
However, Vanvitelli made a number of changes for the Holy Year of 1750. The church contains the altar frontals taken from St. Peter's Basilica when these were replaced with mosaics.
Because Piazza della Repubblica outside joins onto Via Nazionale, the church has become a natural place for celebrations of the Italian State. Three of the great leaders in victories from the First World War- Vittorio Emanuele Orlando, Thaon di Revel and Armando Diaz- are buried inside the church.