The church of Sant’Ansano is located in Casetta, in the district of Dofana, municipality of Castelnuovo Berardenga, in the province of Siena.
Dofana, according to tradition, was the 4th-century scene of the martyrdom of Sant’Ansano, evangeliser and first patron saint of Siena. A church was built on the site of his death, in which his body was kept until the year 1108, when it was moved to Siena’s cathedral.
The oldest thing to commemorate the "ecclesia sancti Ansani" dates to 650. In the Berardenga Abbey’s act of foundation (867), an oratory in Ansano’s name is mentioned among the donations that were made by the Winigis counts. The Oratory of Sant’Ansano underwent its most recent restorations in 1931 and 1980.
By 1504 the chapel lay almost in ruins, and in 1507-08 the Bishop of Arezzo authorised its reconstruction, which some nineteenth-century studies have attributed to Baldassare Peruzzi. The eventual structure was officialised in 1575.
A chapel dedicated to the same saint lies a few hundred metres from the chapel. Octagonal in form, the side opposite the entrance is extended into a rectangular apse. An epigraph there refers to the turn-of-the-century restorations done on the building and also on a Maestà by Pietro Lorenzetti, now kept in the Pinacoteca di Siena.