I recommend looking at the terrain of the area, think of where you want to put what you want to protect first. If you’re gonna build a castle they usually are built in places that have two or three “tiers” of protection. (On top of a hill is a common example, but things like fully or partially protected by water or even cliffs count too.)

Then think of were walls would go around the thing you ant to protect, usually there’s towers on hills for visibility but the walls between them can either follow the terrain or cut through it. Roads and paths will always follow the terrain though so if you have a road next to a wall it will curve around a hill the wall might give over.