Giorgione's town conserves the prestige of a historic centre of art within its medieval walls. Giorgione's altarpiece inside the Duomo and the frieze of Casa Marta Pellizzari lie in the heart of the town alongside the eighteenth century Academic Theatre (Teatro Accademico). Frescoed buildings overlook the spectacular piazza lining the castle walls, built by the inhabitants of Treviso in the 12th century to defend their borders. The unique square of red walls still seems to protect the medieval town as it did at the end of the 12th century when Treviso builders erected the defensive enclosure to guard their territory. The municipal tower rises above the corner towers and the city walls, with an entrances on three sides to the austere fort. Around the castle lies a pleasant garden, surrounded by a moat and a magnificent walk lined by statues.