I went back to the nether and continued working on my "Cinderella Goes Bad" Castle. The first tower took several days to complete due to having to blow out space in the surrounding walls. The new smaller tower went up in just under two hours and would have gone much quicker if I hadn't forgotten half the building supplies.
Anyway. enjoy. both towers are built on a 9-deep lake of lava and are unreachable except by scaffolding. Since no construction is truly impregnible (except hacked bedrock structures), I'm aiming for "as defensible as possible." The amount of time it would take a normal player to scaffold out and up to a level without obsidian would give me more than enough time to mount a defense.
Now that the castle is really starting to go up and I've decided on a theme. I'm thinking about doing a negaverse trick and building a matching castle out of something (Snow, Wool?!?) in the real world with linking Nether portals.