Once host to the Council of Trent, this dimly lit Romanesque cathedral displays fragments of medieval frescoes inside its transepts. Two colonnaded stairways flank the nave, leading, it seems, to heaven. Below is a paleo-Christian archaeological area, which includes the Basilica Paleocristiana di San Vigilio, a 4th-century temple devoted to Trento's patron saint and to a number of Christian martyrs murdered by pagans in the nearby Val di Non.