I'm looking for something like Crocobura's Stone Arch, only one tile wide instead of two.

Also, those skinny slots they used to put in the walls of forts and castles, to allow archers/musketeers to shoot out, without the enemy seeing them, really. They cut into the wall in a wedge shape, to let the shooter cover a range of view from side to side... see screenshot.

They're both things I would have expected to find at MedievalSims, only I can't say that I've ever seen them there.