This is a picture of the Cambridge, Massachusetts National Guard Armory, around 1900. Armories that were built then looked something like castles. They were a place for the Guard to gather and train, but were also considered to be a place to defend against anarchists, communists and radical socialists. the saw-toothed, "crenellated" appearance of the top of the building allowed defenders to either fire at an attacking force or take shelter. Note the windows on the bottom of the building. They could serve as sally ports. Once an attacking mob had scattered, defenders could sally forth in pursuit
