One of the interesting architectural features of the Goffe Street Armory that gives it a mildly medieval or castle-like feeling are the courses of brick corbelling. Brick corbels carry small arches, giving texture and visual interest.
Interior buttresses stabilize the connection between the drill shed (to the left in this picture) and the Headhouse. There are two of these buttresses, which appear as tall arches with port-hole windows above. Here’s a view of the second, looking in the other direction: