I spent about 8 hours hollowing out an entire mountain into a labyrinthine tower of stone rooms. It was pretty awesome, if I do say so myself. I even made a glass balcony and a 10block by 10block picture window about 2/3 of the way up. Incredible views. :P Then I dug out a spiral staircase to a huge room and found lava. I died in it.
[You must be logged in to view images. Log in or Register.]
I really enjoyed it for the creative outlet it is, but won't even consider playing multiplayer until I can protect my castle from being torched and or destroyed by some asshat griefer.
Super cool concept though!