Olongapo, officially the City of Olongapo (Lungsod ng Olongapo; Siudad ti Olongapo; Siyodad nin Olongapo), is a 1st class highly urbanized city in the Central Luzon region of the Philippines. Located in the province of Zambales but governed independently from the province, it has a population of 260,317 people according to the 2020 census. Along with the municipality of Subic, it comprises Metro Olongapo, one of the twelve metropolitan areas in the Philippines. In 1868, a Spanish military expedition was dispatched to study the possibility of relocating the Cavite Naval Station in Subic Bay due to its unhealthy condition. Spanish King Alfonso XII through a Royal Decree made Subic Bay (then called Subig) as Spain's stronghold in the Far East in 1884. Vice Admiral Juan Bautista de Antiquiera made Olongapo a settlement for the Spanish Navy. On March 8, 1885, the Spanish Naval commission authorized construction of the Arsenal in Olongapo. The Spanish planned to make their naval station, and the village of Olongapo an island, protected against attack by rebels. The Spanish Navy Yard occupied the entire area east of the Spanish Gate. Employing Filipino labor, they did extensive dredging of the harbor and the inner basin and built a drainage canal. The canal served both to drain the swampy area around the yard and also to form a line of defense. Within ten years, the Spaniards had erected walls and markers to fence off the arsenal. They had shops and buildings erected. The Spanish government spent almost fifteen years developing the naval station. From higher naval commands, the order was sent to fortify Grande Island at the mouth of Subic Bay with mines and cannons. But this project was hardly begun before it was overtaken by the rout of the Spanish Navy in Manila Bay by US Admiral George Dewey. On May 1, 1898, the construction of the Spanish Administration Building was nearly complete when Admiral Dewey's flagship, , led the Asiatic Fleet into Manila Bay. A detachment of Admiral Dewey's fleet bombarded the navy yard.