Corregidor Island locally called Isla ng Corregidor, is an island located at the entrance of Manila Bay in southwestern part of Luzon Island in the Philippines. Due to this location, Corregidor has historically been fortified with coastal artillery to defend the entrance of Manila Bay and Manila from attacks by enemy warships. Located 48 kilometres (30 mi) inland, Manila has been the largest city and the most important seaport in the Philippines for centuries, from the colonial rule of Spain, Japan and the United States, to the establishment of the Philippines in 1946.

Corregidor (Fort Mills) is the largest of the islands that formed the harbor defenses of Manila Bay together with El Fraile Island (Fort Drum), Caballo Island (Fort Hughes) and Carabao Island (Fort Frank), which were all fortified during the American liberation of the country. The island was also the site of a small military airfield, as part of the defense.

During World War II, Corregidor played an important role during the invasion and liberation of the Philippines from Japanese forces. Heavily bombarded in the latter part of the war, the ruins left on the island serve as a military memorial to American, Filipino and Japanese soldiers who served or lost their lives on the island. Corregidor is one of the important historic and tourist sites in the country.

According to wikipedia