The tall walls of this bastion, built between 1470 and 1630, rise just behind the cathedral. Within the walls are an open-air theater, the Cortile delle Milizie, where a summer film-and-concert festival is held, and a museum. But the walls themselves steal the show. A walk along them affords views over Trieste and the Adriatic, making this a popular spot just before its sunset closing time. The Civic Museum provides an interesting, if not profound, experience -- among a series of period rooms is a "Venetian chamber" filled with antique chests, 17th-century Flemish tapestries, and other furnishings -- as does the Appartamento del Capitano, the residence of the castle's 18th-century commander. A collection of antique weaponry is housed in the rooms of the castle watch.