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Fort Barrancas or Fort San Carlos de Barrancas is a United States military fort and National Historic Landmark in the former Warrington area of Pensacola, Florida, located physically within Naval Air Station Pensacola, which was developed later around it.The hill-top fort, connected to a sea level water battery,

overlooks Pensacola Bay. From 1839 to 1844, the historic Spanish fort on the hill was reconstructed and dramatically expanded in brick. This is now termed "Fort Barrancas". The older, water battery downhill has been separately named as "Fort San Carlos".

It is a remnant from the Spanish fortification, the wooden Fort San Carlos de Barrancas of the late 18th century.

Source: Wikipedia