Here's the shot I have in my archives - taken December, 2000 using a PhotoSmart C200 (now that's old!!). Same fort (Fort Mantanzas), different guardhouse facing away from town.
I'm pretty sure his is the Castillo de San Marcos, not Fort Mantanzas. Both are very similar, but notice the lighthouse in his shot? I'm very familiar with both forts. Someone correct me of I'm wrong.