Anyone have any good tips on building castle walls with practicality in mind?
On my server's survival world, we have a large, flat, walled-off area. The walls are made of cobblestone, are one block thick, and are four blocks tall, so falling off of them gets you half a heart of fall damage (gotta fix that...). There is a one-block overhang on the outside and a three-block overhang on the inside. There are pairs of doors periodically placed along the wall, though perhaps not periodically enough.
At the moment, going in and out of the castle is a tad dangerous. You never know if there is a creeper right around the corner just waiting to give the castle a brand new doorway or a skeleton archer who thinks your face could use a few arrows sticking out of it. Spiders are also really annoying because they will often float up the wall and hover above the doorways, waiting to give someone's brains a shot of spider venom.
So aesthetics completely aside, what is the best and most practical way to build castle walls for functionality and safety?
How about making the wall three blocks thick, with the inner layer being sand (or gravel).
If a creeper makes a hole in the wall, the sand will plug it up.