Piazza del Duomo The large Piazza del Duomo, dominated by the cathedral, is lined with other medieval buildings, such as the Palazzo del Comune and the Palazzo del Podestà it is the setting (in July) of the Giostra dell'Orso ( Bear Joust ), when the best horsemen of the d city's traditional quarters tilt with lances at a target held up by a dummy shaped like a bear.