Work on St. Augustine’s church began starting from the middle of the 13th century (1258) and, according to some documents in the archives, it was still uncompleted in 1309. Between 1450 and 1485-’90 the building underwent extensions and refurbishing which lead to the completion of the last chapel on the right of the transept (the Bichi chapel), brought back to its original forms just a few years ago.
The inside , the church as we see it today, is the work of the architect Luigi Vanvitelli (1700-1773) who, called in 1755 to intervene upon the building’s structure which had been devastated a few years earlier by a disastrous fire (1747), was able to carry out a perfect blend between the neo-classical lexicon of the new architectural elements and the monumentality of the 16th-17th-century altars already present.
The entrance portico was made between 1818 and 1819 by the Sienese architect Agostino Fantastici.