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Fort Point Light is located on a masonry fortification on the south side of the Golden Gate at the entrance to San Francisco Bay, California. The fort was completed just before the American Civil War by the U.S. Army to defend San Francisco Bay against hostile warships. The fort is now managed by the U.S. National Park Service as a unit of the Golden Gate National Recreation Area.
In 1769, Spain claimed the San Francisco Bay area and by 1776 had established a mission and a presidio. To protect against encroachment by the British and Russians, Spain selected the promontory at the narrowest part of the bay's entrance for a fortification called Punta del Cantil Blanco, for the high white cliff. Following the Mexican American War, and the annexation of California, the U.S. military recommended a series of fortifications to protect San Francisco Bay. Fort Point was selected as a site that would defend the maximum amount of harbor area. The design specified that the lowest tier of artillery be as close as possible to water level so cannonballs could ricochet across the water's surface to hit enemy ships at the waterline. To achieve this, workers had to first blast the 90 feet (27 m) high white cliffs down to 15 feet (4.6 m) above sea level.
Three lighthouses have historically been located at Fort Point. The original lighthouse, built in 1853, was torn down to make room for the Army fort. The second lighthouse was built on a narrow ledge between the fort and the ocean, but erosion undermined its foundation, and in 1863 it was torn down to make way for a bigger seawall. The third lighthouse was built atop the wall of the fort in 1864. On September 1, 1934, after the towers for the Golden Gate Bridge were built, the lighthouse was deactivated since the bridge would block off much of the light from the lighthouse. Read more here and here. Explore more of Fort Point here: