There are lots of architectural mysteries at Fort Pickens. Most of them stem from damage done long after the fort was completed in 1834.
In the wake of the Civil War, Pickens and her sister forts were obsolete. They had been proof against the cannons and ships of their day, when smoothbore cannon and sails were high-tech. Now, however, rifled guns capable of firing much larger rounds and steamships using propellers were better able to stand up to a masonry fort--or simply motor past it against winds and tides.
In the years that followed, guns and ships quickly evolved. Fortification had to keep pace, as it had centuries before. Brick gave way to concrete. Forts gave way to buried bunkers. The massive two-gun Battery Pensacola was built within the walls of Pickens, stretching diagonally across the parade ground. The guns' powerful blast kicked up a cloud of sand on top of the fort every time they fired. The tops of the old fort's walls inhibited the guns' field of fire.
No respecters of old architecture, those Army types. They had Engineers dynamite the south and southwest walls and bastion 'B' in 1916. The Pic of the Day shows what's left of the south cistern, where rainwater was collected for drinking. The blasting knocked the facing off, exposing its twin arches. There used to be a pair of stairways here--one running up to the left, parallel to the cistern's face along the south wall, the other where the wall stands in the middle of the frame. That one always confused me, since the wall isn't part of the original structure. It's clearly old brick, maybe picked from the rubble after the blasting. It's not propping up the arch to the right. There's a big pile of sand and brush behind it. The only thing that makes sense is that it's there to keep people from climbing around back there or up on the walls and bastion in that area.
I wonder how much of the original stairway is under all that.