A mélange of building styles and constant modifications characterize this huge palace dating from the 13th to 15th century. When Bologna was an independent city-state, this was the seat of government—a function it still serves today. Over the door is a statue of Bologna-born Pope Gregory XIII (reigned 1572–85), most famous for reorganizing the calendar. There are good views from the upper stories of the palace. The first-floor Sala Rossa (Red Room) is open on advance request and during some exhibitions, and the Sala del Consiglio Comunale (City Council Hall) is open to the public for a few hours in the late morning. The old stock exchange, part of the Palazzo Comunale, which you enter from Piazza Nettuno, has been turned into a library. Dubbed the Sala Borsa (www.bibliotecasalaborsa.it), it has an impressive interior courtyard. Within the palazzo are two museums. The Collezioni Comunali d'Arte exhibits paintings from the Middle Ages as well as
some Renaissance works by Luca Signorelli (circa 1445–1523) and Tintoretto (1518–94). The Museo Giorgio Morandi is dedicated to the 20th-century still-life artist Giorgio Morandi. Underground caves and the foundations of the old cathedral can be visited by appointment made through the tourist office.