Cortona is one the main cultural and tourist centres in Val di Chiana. This city was an Etruscan settlement: of great importance are the archaeological sites of the Etruscan graves dating back to VII-IV century B.C. in the hamlet called Sodo (said "Melons" by local people for their particular shape) and the remains of the walls. In the twelfth century Cortona became a free city renowned for its arts and its crafts; it lost its independence in 1411, when it was sold to Florence. This city preserves extraordinary historical and artistic treasures, such as the precious palaces of the wealthy medieval aristocracy (among them, Casali Palace and Sernini Palace). Cortona also hosted famous artists such as Signorelli, Laparelli and Berrettini. The halls of the Museum of the “Accademia Etrusca” preserves an interesting collection of Etruscan and Roman archaeological finds, and the Diocesan Museum houses one of the most beautiful Annunciation by Beato Angelico. Cortona also boast of splendid churches, like St. Francis, the Duomo, Santa Maria delle Grazie in Calcinaio, the Franciscan Sanctuary of “Le Celle” and the beautiful Sanctuary of Santa Margherita, for which the local population has a particular devotion. An event hosted by this city is Cortonantiquaria, one of the most interesting national antique fairs.