Here is a sample of Walls and Towers I have made, which maybe you guys can use in your future builds.

These are great for Faction world forts on multiplayer servers, as they have 3 layers and use stone, which is great for preventing TNT Cannons.

The towers can be used as effective sniper spots if you are ever being attacked.

These designs are also nice looking, and would serve for a good purpose in any fantasy style builds.

The map is available to download, so you can take a look at the design a little better than the pictures provide.