The Borgo di Sesto of pre-Roman origin saw its greatest development thanks to the foundation of the Benedictine Abbey in the first half of the 8th century and the Longobard donation in 762, which was followed by numerous others. In 899 it suffered the devastating Hungarian invasion and was rebuilt and fortified from 960 onwards, taking on the appearance of a medieval castle with a defensive system of towers and moats. In 1420 it passed from the Patriarchate of Aquileia to Venetian rule until the Commenda was suppressed in 1784. Inside the basilica, worth seeing are the remarkable frescoes of the Giotto school, the urn of St Anastasia preserved in the crypt, the 15th-century Vesperbilt and the Annunciation of 1300. In the Abbey Square you can admire the Palazzo del Comune, former residence of the abbots, the Abbey Chancellery, seat of civil power in medieval times, and the 11th-12th century bell tower, which together with the Grimani tower is the only surviving one of the seven defence towers that surrounded the monastery.