Pyramids are structures that can be made in Stronghold and Stronghold Crusader in the map editor(Although they can be made during skirmishes and missions). They are built by placing a single tile of Wall on the highest elevation and lowering all the surrounding land. Stairs are then dropped from the wall to the ground along the four main directions, and finally the gaps are filled in with stairs. Invented by Alex Klotz.
But, if you place a wall on medium terrain, then reduce the med height by roughly 50 clicks, you can create a pyramid that has flat edges, not stairs, which change into odd directions.