The basilica of Santi Cosma e Damiano
is one of the ancient churches of Rome. The basilica, devoted to the two Greek brothers from Syria, doctors, martyred under Diocletian, saints Cosmas and Damian, is located in the Forum of Vespasian, also known as the Forum of Peace.
For reference, a plan of the church is available here
The body of the church was built by Vespasian (69-79) as the templum alma urbis to conserve censorial records, municipal street plans, etc. The circular vestibule opening onto the Forum was constructed by Maxentius. Originally, the external wall was clad with about 150 marble slabs incised with a street map of Rome at the time of the Severi (3rd century AD) known as the Forma Urbis.
The hall was Christianized and dedicated to Sancti Cosma et Damiano in 527, when Theodoric the Great, king of the Ostrogoths, and his daughter Amalasuntha donated the buildings to Pope Felix IV (526-530). The pope united the two buildings to create a basilica devoted to the two Greek brothers and saints. The sacred building was enlarged in 695, under Sergius I and in 772, during the pontificate of Hadrian I, serving as a reception center for the poor and pilgrims. In 1512 Cardinal Alessandro Farnese (future Pope Paul III) entrusted the complex to the Third Order Regular of St. Francis (TOR), who are still in charge.
In 1632, Pope Urban VIII Barberini ordered the restoration of the basilica. The works, which were designed by Orazio Torriani and directed by Luigi Arrigucci, raised the floor level 23 feet, thus avoiding the infiltration of water. Also, a cloister was added.
In 1873 the church was expropriated and confiscated from the state property of the Kingdom of Italy, then it passed into that of the Italian Republic, which still manages it today through the Fondo Edifici di Culto (FEC). In 1947, the restorations of the Imperial Forums gave a new structure to the church. The original access, which took place from the ancient "Via Sacra", through the splendid portal of the "Temple of Romulus", was closed and replaced by a new entrance, designed by Gaetano Rapisardi, with a travertine arch on via dei Fori Imperiali.