The **Basilica of San Martín de Mondoñedo**, located in Foz, is officially recognized as the oldest cathedral in Spain. This 11th-century Romanesque jewel stands as a testament to the early spiritual and political power of the Kingdom of Galicia. Its architectural robustness, characterized by thick granite walls and semicircular apses, hides an interior of surprising artistic richness, including 12th-century murals and historically significant capitals. According to legend, the site is linked to the "Miracle of the Ships" by Saint Gonzalo. Today, the complex houses a fascinating parish museum that explains its evolution from an episcopal seat to a pilgrimage destination. Visiting San Martín is more than a tourist stop; it is a journey to the very roots of Christianity in the northern Iberian Peninsula, surrounded by a serene landscape that invites contemplation.