The church of Sant'Agostino was built with an adjoining convent from 1258. Construction continued for more than fifty years, with extensions and remodelling over the centuries, especially during the 15th century, between 1450 and 1490. After a disastrous fire in 1747, it required a complete renovation, which was supervised by Luigi Vanvitelli, from 17 July 1747 to 1755. At the beginning of the 19th century, with the Napoleonic suppression of religious orders, the Augustinians left the convent.
The Cathedral of Santa Maria Assunta was built in the 13th century in the Romanesque-Gothic Italian style. It is famous for its intensive use of marble marquetry. An enlargement of the church took place in the 14th century, but was abandoned with its failure. As part of Historic Centre of Siena, the cathedral is a UNESCO World Heritage Site.
The Basilica of San Domenico was built in the 13th century and enlarged in the following century. The Gothic building houses the relic of the head of Saint Catherine of Siena in a splendid Renaissance chapel built for the occasion.