This is a humble post on some castle and fortification architectural terms - specifically, walls. When writing, sometimes I cannot find the right word for a… *flails hands* thing, and I like to be accurate, when possible. This is not The Definitive Post on Castle Architecture. I’m sure someone else has made such a thing and they deserve applause.
A balustrade is a railing piece along a bridge, stair or balcony. It is supported by balusters, which are short, typically decorative columns. Balustrade may also refer to the entire column/railing construction. Balusters along a stairway are often called bannisters.
A parapet is a short, protective barrier, usually no more than head-height, along a terrace, balcony or roof. When a parapet is crenellated, meaning it has indentations at regular intervals, it is called a battlement. The gaps in a battlement are called crenels or embrasures; the solid upright sections (the not-gaps) of a battlement are called merlons.
A bulwark is any kind of defensive wall or embankment. A bastion is a structure projected outward from a castle or fortification. The connecting wall between bastions or towers is a curtain wall.
A rampart is a thick defensive wall with a broad top, which is often crowned with a parapet or battlement. A chemin de ronde is a protected walkway atop a rampart and behind a battlement, sometimes called a wall-walk if you don’t want to sound too fancy.
There are many more parts to castles and other fortifications. Explore them and enjoy. But if this helps anyone just a little, I will be pleased.