We have crenelations, yes, we do, we have crenelations, how bout you?
Since the resolution of the light gauge steel problems things have started moving pretty fast. The crenelations have gone up in a few days. Next will be the front tower 4th floor framing, then, or concurrently, chimney chases and rear tower framing, and we should be about ready for our roof membrane.
People the world over recognize crenelations as one of the quintessential characteristics of a castle, and it is a personal pet peeve of mine when people try to mimic them without the proper scale. These were meant to hide defenders, so unless your castle is being defended by the lollipop guild you need them to be pretty big, mine are. They are a functional part of a castle, not decorative.
The tooth part is called a merlon, the gap is called a crenel, and whole thing is a crenelated battlement, you could also possibly say a crenelated parapet wall. Additionally it is cantilevered, which means it projects beyond its lower supporting wall. This cantilever was done to provide space for little gaps at the base of the wall, called machicolations, that provided an avenue for dropping rocks or oil down on ladder climbing attackers (while not having to expose yourself over the top of the wall). We will not be having the machicolations, but we will be adding corbels to complete the cantilevered look.