Lined with fine ancient buildings, Plaza del Cabildo is the heart of Arcos' old town, its vertiginous mirador affording exquisite panoramas over the Río Guadalete. The Moorish-origin Castillo de los Duques, rebuilt in the 14th and 15th centuries, is closed to the public, but its outer walls frame classic Arcos views. On the square's eastern side, the Parador de Arcos de la Frontera is a reconstruction of a grand 16th-century magistrate's house; pop in for a drink.
Bordering the plaza's northern edge is the Gothic-baroque Basílica Menor de Santa María de la Asunción.