The Parish Church of Sant’Innocenza is a sacred building located in Piana, a hamlet in Buonconvento. It was fortified by Santa Maria della Scala, a hospital in Siena. It was the summer residence of the Bishops of Siena and Popes Pius II and Paul III were hosted here on separate occasions.
Documented as early as 1081, the fortified structure has a Latin-cross plan, with the typical characteristics of Sienese military architecture of the 13th-14th centuries; one side was built from the church. Made in baked clay like most of the complex, but with rows of stone on the bare façade, the church has a single nave with exposed trusses, though it also contains a few Gothic elements in the four-sided chapel at the end of church, covered with a barrel vault, where the figure of Beato Franco da Grotti still remains.
Flanking the parish church is a large brick building with a high scarp, which conserves the medieval defensive structures in one part, comprising a protruding apparatus with a corbel and a double row of bricks for the small arches, typical of Senese fortifications in the 14th century. A large, jutting tower still stands in the eastern corner. The tower is separated from the parish church by a 16th-century courtyard, which can be accessed through an arched doorway, flanked by a stone tower base, on top of which a brick bell tower was built in the 1500s.