The circular building at the entrance onto the Forum (not used today) was built in the early 4th century as a Roman temple, thought to have been dedicated to Valerius Romulus, deified son of the emperor Maxentius. The main building was perhaps the library of an imperial forum.It became a church in 527 and contains important but much restored early Christian art, especially in its mosaics.Today it
is one of the ancient churches called tituli, of which cardinals are patrons as cardinal-deacons: the current Cardinal Deacon of the Titulus Ss. Cosmae et Damiani is Beniamino Stella, created Cardinal on 22 February 2014. The basilica, devoted to the two Greek brothers, doctors, martyrs and saints Cosmas and Damian, is located in the Forum of Vespasian, also known as the Forum of Peace.HistoryThe Temple is traditionally held to have been dedicated by Emperor Maxentius to his son and co-consul Valerius Romulus, who died in 309 and was given divine honours. The temple building was probably part of a rebuilding program of "incredible intensity" undertaken by Maxentius in the area, following a disastrous fire in 306; the project was only part-complete at his death. The temple's identification with Valerius Romulus is tentative, based on the spot-find of a coin dated to 307 AD showing the distinctive shape of the building, and a nearby dedication to Valerius Romulus as a a divinised mortal. The temple has also been speculated as a rebuilding of the original temple of "Jupiter Stator", or one dedicated to Penates, restored by Maxentius.