It has Etruscan-Roman origins, with a nearly entirely preserved circle of walls dominated by the Cassero (donjon). Recent excavations have discovered a V cent. BC sacred area. The Pinacoteca Comunale contains valuable works of jewllery of the XIII cent. and paintings by Margarito, Taddeo Gaddi, Bartolomeo della Gatta and Giorgio Vasari. The XVI cent. Loggia of the Palazzo Comunale, like a balcony, provides a view of the valley of Chio, the natural link between the Valdichiana and the Valtiberina. In the month of May, during the “Maggio Castiglionese”, many culture,sport, music and food-and-wine events take place. On the third Sunday of June the Palio dei Rioni Castiglionesi, a horse tournament, is held in Piazza Garibaldi outside the walls.