Fort Amador and Fort Grant were former United States Army bases protecting the Pacific (southern) end of the Panama Canal at the Panama Bay. Amador was the primary on-land site, lying below the Bridge of the Americas. Grant consisted of a series islands lying just offshore, some connected to Amador via a causway. Fort Sherman was the corresponding base on the Atlantic (northern) side. All of the Forts were turned over to the Republic of Panama in 1999, and the area is now a major tourist attraction.
The offshore islands had always been considered excellent defensive grounds, and were long visited by English pirates. In particular Sir Francis Drake, Captain Cook, and Henry Morgan all used Taboga and Perico as refuges after raiding Spanish galleons. It was here that then-Captain Ulysses S. Grant ended his cross-Panama march in 1852.
During the construction of the Canal, notably the Culebra Cut, waste material was dumped in a mangrove bush then known as the "Balboa dump". As the work progressed the dump was backfilled to create a large breakwater, which was later extended to the nearest of the offshore islands, Naos. This work was completed in 1912, and the Military Reservations were given their official names that year. Fort Amador is named for Manuel Amador Guerrero, the first president of Panama, while Fort Grant was named to commemorate Grant's earlier crossing to that point.
The two Forts initially claimed only about 70 acres (280,000 m2) of land, but this expanded over the years to over 344. Amador was the primary infantry and support area, and grew to include a rather prominent "tank farm" for fuel storage. Grant was primarily for naval defence, and included a number of large batteries on the various islands. To supply them, the causeway was extended to connect from Naos to the other nearby islands, Culebra, Perico and Flamenco, all of which had batteries of various sizes. Grant also included the nearby unconnected islands of San Jose, Panamarca, Changarmi, Tortolita, Torola, Taboga, Cocovieceta, Cocovi, and Venado.