The Basilica of St. Mary of the Angels and the Martyrs

In the sixteenth century the central part of the magnificent Baths of Diocletian were converted into a church by Michelangelo. The church, dedicated to the holy angels and martyrs, gives a good impression of the sheer size of some of the Romans’ thermal bath complexes.

The baths of Diocletian fell into disuse in the sixth century after the Goths cut off the water supply. For centuries the baths were plundered first by invading barbarians and later by the Romans themselves who used the ruins as building materials for the construction of new buildings. Nevertheless a large part of the structure is still intact, albeit devoid of any ornamentation.

In 1561 pope Pius IV entrusted Michelangelo Buonarotti with the task of building a church inside the ruins of the ancient bath complex.Impetus for this dedication had been generated by the account of a vision experienced in the ruins of the Baths in 1541 by a Sicilian monk, Antonio del Duca, who had been lobbying for decades for papal authorization of a more formal veneration of the Angelic Princes. It was also a personal monument of Pope Pius IV, whose tomb is in the apsidal tribune.

Construction and remodeling

Michelangelo was already eighty-six years old at the time and this would be his last architectural project. He opted for a floor plan in the shape of a Greek cross, with a nave and transept of equal length. He incorporated the church building into the former frigidarium, leaving the Roman structure more or less intact. By the time of Michelangelo’s death in 1564 the church was still unfinished but his plans were implemented by one of his pupils, Giacomo del Duca, who happened to be a nephew of Antonio Lo Duca.

In the eighteenth century Michelangelo’s design was modified by Luigi Vanvitelli, who moved the main altar and changed the orientation so that the original transept is now the nave. The Napolitan architect also added decorative elements such as plasterwork and he added eight more columns identical in appearance to the original Roman ones. In addition, Vanvitelli also built a new front facade.

Vanvitelli’s facade was removed in 1911 so that the entrance facing Piazza della Repubblica looks again unadorned as was intended by Michelangelo. The current front facade is actually an exedra that was part of the caldarium. The bronze doors are modern and were created by Igor Mitoraj, a Polish sculptor.

The circular vestibule (the former tepidarium) holds a statue of St. Bruno, created by the French sculptor Jean-Antoine Houdon. The church was assigned to the Carthusian order, which was founded by the saint. The vestibule has a beautiful coffered dome ceiling.

Nave and transept

Once inside the nave, one gets an idea of the astonishing size of the ancient Roman baths. The church, which only occupies the central part of the baths, is over ninety meters wide. The cross-vaulted ceiling over the transept is twenty-eight meters above the floor, which was elevated more than two meters so as to protect the church against rising moisture.

As a result only about fourteen meters of the seventeen-meter tall columns are visible. The original Roman bases are hidden under the floor and were replaced by reproductions. The massive red granite columns, the largest in Rome, measure 1.6 meters in diameter. Only the eight central columns are from the Roman era. The others are skilful imitations in plaster; it’s surprisingly hard to tell them from the originals.

Paintings

The painting of the seven archangels and Mary that inspired Antonio Lo Duca is now the main altarpiece. The painting is framed with sculptures of angels.

Linea Clementina

On the floor in the right transept you can see the Linea Clementina, the meridian of Rome. Until 1846 the meridian was used by Roman citizens to set the time. A small opening in the roof causes sunlight to fall on the line right at noon.

The meridian was created in 1702 by the astronomer Francesco Bianchini on behest of pope Clement XI, as part of a project to improve the accuracy of the calendar. Along the line are marks indicating the zodiac signs.