Michelangelo was commissioned to build this church at the age of 86. After his death, the project lost its architectural unity leading to an unorthodox building. Heavily remodelled in the 18C by Neapolitan architect Luigi Vanvitelli, the church was stripped of its façade in the 20C, exposing the brute form of the caldarium of the Baths of Diocletian. The colossal size of the latter can be felt inside the church, its huge transept giving an idea of the majesty of the original Classical structure.