(Collecta: S. Crisogono in Trastevere)
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From Blessed Ildefonso Schuster's The Sacramentary:
The basilica of St. Chrysogonus in Trastevere stands on the same spot as the former house of the martyr, of which the rooms were used to form the sanctuary or crypt under the high altar. The church is claimed to have been built under Constantine, and the veneration paid to St. Chrysogonus was so widely spread in Rome in the fourth century that his name is still to be found in the diptychs of the Roman Canon.
The stational Basilica of St. Mary in Trastevere is one of the most ancient in the city, and may be considered as a continuation or enlargement of the titulus Callisti, which is quite near it.
We know for a fact on the authority of Lampridius that Alexander Severus confirmed by a legal decree the right of the Christians to the possession of a meeting-place in the Trastevere, which had been contested by the popinarii of the Taberna emeritoria. Ancient documents identify this place with the titulus Callisti, from which, strictly speaking the actual Basilica Julii built juxta Callistum by Pope Julius I (341-352) should be distinguished, though the two buildings were so close together that in the Middle Ages they formed but one edifice...
An ancient tradition says that on this spot Pope Callixtus (219-24) died for the faith, being thrown into a well...
The body of Callixtus, together with those of the martyred priest Calepodius and Pope Julius I, now lies under the high altar...
From the Churches of Rome wiki:
The church was one of the tituli, the parish churches of ancient Rome, known as Titulus Callisti. It is possibly the first church in Rome where Mass was celebrated openly. It was probably built by Pope Julius I (337-352), although tradition claims that it may have been built before 313, perhaps as early as soon after Pope Calixtus' death in 222 [1]. He was martyred near this place, and the titulus may have been named after his rather than the owner because it was originally built as a memorial chapel. It is believed to be the first church in Rome dedicated to the Blessed Virgin.
It was rebuilt under Pope Innocent II (1138-1148), in the first years of his pontificate. He kept the basilical plan, at a time when the Gothic style was gaining popularity in Northern Europe.
In the 1860's, it was restored with mixed results.
During some Holy Years, when the plague or flooding prevented the use of the churches outside the walls, this church was counted among the seven churches in the pilgrim itinerary.
