The original church of Sant' Agostino di Vagli, dedicated to San Regolo, consisted of a building with a rectangular plan and a single
apse corresponding to today's
nave. The ancient entrance, a
portal with a
round arch like the one on the south side, can still be seen on the façade. The building was later enlarged, with the addition of an aisle closed by a semicircular apse, probably when the Augustinian nuns took over the church at the end of the XIV century.
In the XVII
th century some works were carried out, among which important repairs to the roof, while other restorations date to the last century when a cavity wall was built on the north side of the church. Recent excavations near the church have brought to light a XIII-XVI
th century necropolis.