At the southeastern end of town near the waterfront is this solid and squat building, partially restored to maintain its historic character. Inside is a museum with several impressive and recently renovated galleries. The marine exhibit includes some sophisticated displays, and across the inner courtyard is a terrific ethnographic gallery on the boat-dwelling Sama Dilaut (otherwise known as the Badjao, or sea gypsies). Walk around the ramparts for 360-degree views of Zamboanga City and the busy ocean.
Other galleries include an exhibition of 18th- and 19th-century prints and the 'Southern Philippines: Portal and Nexus of Barter Trade & Exchange'. The fort's chequered past is also worth noting: founded by the Spaniards in 1635; attacked by the Dutch in 1646; deserted in 1663; reconstructed in 1666; rebuilt in 1719; stormed by 3000 Moros in 1720; cannonaded by the British in 1798; abandoned by the Spaniards in 1898; occupied by the US in 1899; seized by the Japanese in 1942; and, finally, claimed by the Philippines in 1946.