The Sé de Viseu is the ancient heart of the city, a Romanesque cathedral founded in the 12th century on a hill above the old town. The exterior is relatively plain — granite, sober, Portuguese — but step inside and the Manueline vaulting of the nave stops you in your tracks: elaborate stone ribs twist above the nave in a pattern of ropes and maritime symbols that seems almost organic.
The cathedral treasury holds a good collection of ecclesiastical objects, and the Gothic cloister is quiet and handsome. The cathedral sits at the top of the Adro da Sé, the city's most elegant square, flanked by the Misericórdia church and the Grão Vasco Museum. The square itself is worth sitting in, especially in the evening when the granite glows warm in the low light.