The first Saint-Rémy church, of which only the tower remains today, was built in the 13th century. It was built at the foot of the hill on which stands the castle. The church gradually fell to ruins and the new Saint Rémy church was built in the heart of the town. It was Thomas Bouchard, deputy mayor and treasurer of the parish who laid the first stone in 1522. The gothic centre, surrounded by an ambulatory and radiating chapels, was completed in 1545, but the influence of the first French Renaissance was already visible in the décor.References:
The Basilica of Santa Maria in Trastevere is one of the oldest churches of Rome. The basic floor plan and wall structure of the church date back to the 340s, and much of the structure to 1140-43. The first sanctuary was built in 221 and 227 by Pope Callixtus I and later completed by Pope Julius I.
The inscription on the episcopal throne states that this is the first church in Rome dedicated to Mary, mother of Jesus, although some claim that privilege belongs to the Basilica di Santa Maria Maggiore. A Christian house-church was founded here about 220 by Pope Saint Callixtus I (217-222) on the site of the Taberna meritoria, a refuge for retired soldiers. The area was made available for Christian use by Emperor Alexander Severus when he settled a dispute between the Christians and tavern-keepers.
The church underwent two restorations in the fifth and eighth centuries and in 1140-43 it was re-erected on its old foundations under Pope Innocent II.