Formerly the seat of the bishops of Montalcino, since 1986 it has been a co-cathedral in the Archdiocese of Siena-Colle di Val d'Elsa-Montalcino.
It was demolished and rebuilt between 1818 and 1832 in the Neo-Classical style to plans by the Sienese architect Agostino Fantastici.
On the front altar, is a painting of Saint John the Baptist in the desert, another early work by Francesco Vanni.
On the altar in the Chapel of Suffering is a painting of the Sienese school of the last quarter of the 16th century, derived from Beccafumi, of Saint Michael the Archangel driving the rebellious angels from Paradise.
In the first chapel of the northern nave some fragments have been reassembled of a travertine sculpture depicting Christ in a mandorla almond between two angels with thuribles, from the second half of the 11th century, which originally formed part of the portal of the ancient pieve which survived until 1817, when it was demolished.