I see two options:
Haha, it’s definitely not painted on, so life escape it is.
Assuming it was once a fire escape, it’s a weirdly internal-looking door for something that leads to fuck all.
Maybe used to be a balcony there?
Bugs Bunny: “Watch that first step, it’s a doozy!”
Kifflom!
I've built similar structures in dwarf fortress for taking care of prisoners.
