Mine is built into a mountain...it probably spans a couple biomes, if I am using that term correctly. I rarely go down to the bottom floor, because I usually get lost. The world spawned a gigantic cavern underneath several mountains, and I just have been digging into it for a long time. I've needed to patch it several times--its no means mob-proof, but almost.
It's not really a house as it is more like a fortress.
There's a couple entrances that are hidden underwater, and a powered rail that took forever to mine for and build. Pretty sure the surrounding area of my main spot has no gold left lol. The world spawned an incredible amount of redstone and iron, however. Was quite strange. Looks better than gargamel, imo.