Tui and Valença are united by a single river, whose banks change colours on official maps. In truth, they are identically green and blue without banks. The Episcopal city and capital of one of the provinces of the Ancient Kingdom of Galicia is well worth a visit on its own merits due to its historical district, which has been proposed as a World Heritage site. The tour of the monuments might begin from the central Paseo da Corredoira. The web of narrow and arcaded streets swirls around the Cathedral-Fortress which dominates the long curve of the river from above. The night-time illumination of the exterior walls gives an idea of the defensive appearance of the site.