I drew this map ages ago, but never posted it until now. It’s a small guardhouse, somewhere underground.
Players approach from the west and have two sets of guarded doors to get through, while the guards can harras the players through the arrow slits and the bars.
The above image is 72dpi on a 5mm grid, with 5mm representing 5 feet.
The image below is the 300dpi version, better for printing.