So I have a world and I'm trying to decide what to build on my fort. So far I have the wall up. People are able to walk atop of the wall and there is a place beneath the wall (in between the front half and the back half) for the "guards". It's basically all wooden planks, but every tree is a smooth stone layer for support, there's a gate and some towers. I have dark woods for the corners of the towers, etc. So what should the top floor (the outing) of the wall be where the guards walk? Cobblestone?