Vigo's Casco Vello—Old Quarter—sits on a granite slope that has watched Atlantic fishing fleets depart for five centuries. The district's narrow stone lanes, built without vehicles in mind, climb from the commercial port at Porta do Sol to the Castro fortress, a 17th-century watchtower that once scanned for Barbary corsairs and English privateers. Today the fortress offers a 360-degree panorama: the Cíes Islands float on the Ría de Vigo estuary to the west, while the modernist Fishermen's Neighborhood stretches along the eastern waterfront. Vigo became Galicia's largest city not through conquest or royal decree but through oyster cultivation, sardine canning, and transatlantic emigration routes that connected the port to Buenos Aires and Havana. English-speaking walking tours operate daily from Praza Porta do Sol, the central square where fishmongers once auctioned their morning catch. Guides interpret the modernist facades along Rúa Príncipe—designed in the 1920s when Vigo's shipyards were outfitting steamers—and the Baroque Co-Cathedral of Santa María, whose altarpiece survived a 1719 English naval assault. The district's toponymy reveals maritime memory: Rúa Pescadería (Fishmongers' Street), Praza da Pedra (Stone Square, where granite ballast was offloaded), and Rúa Real (Royal Street, the customs route). Free walking tour Vigo English options typically cover two kilometers over two hours, ascending to Castro for estuary views and descending through Plaza de la Constitución, where wrought-iron balconies frame century-old cafés. The tip-based model—common across Iberia—allows participants to determine value after the experience. Guides, often history graduates or licensed interpreters, provide context that static plaques cannot: the role of Vigo's merchant guilds in resisting Napoleonic occupation, the postwar fishing boom that tripled the population between 1950 and 1980, and the contemporary tension between heritage preservation and port expansion. The walks avoid vehicle traffic by threading lanes too narrow for cars, pausing at miradouros—viewpoints—where Atlantic light shifts hourly across the ría. Praza da Estrela, a pocket square named for a 16th-century inn, serves as a common midpoint; here, guides explain how Vigo's neutrality during World War I made it a coaling station for both Allied and Central Powers vessels. Vigo's English walking tours also interpret the city's relationship with the sea through architecture: shipowners' stone mansions on Rúa Teofilo Llorente, their balconies cantilevered to maximize harbor views; the wrought-iron Mercado da Pedra, a 1920s market hall where Atlantic catches are still sold at dawn; and the waterfront promenade, recently redesigned to reclaim space from industrial docks. The Castro fortress, accessed via stone steps or a public elevator, anchors most routes—not for its military history alone, but for the way its vantage point renders Vigo's geography legible: a natural deepwater harbor, protected by barrier islands, open to westerlies that carried explorers toward the Americas.