I went to Fort Desoto, located in Pinellas County on 8/17/2016.
According to the Ghosttown website,
This abandoned fort is now a County Historical Park. Construction began in 1898, just after the Spanish American War, to protect the coast from a navel assault. The fort never saw any action and was deactivated in the 1920s. There are still gun emplacements with thick concrete walls supported by soil. It was a sister fort to Fort Dade on Egmont Key. By Mike Woodfin