When I first started playing Minecraft, I was on Peaceful difficulty learning the game, though still extremely paranoid about monsters. I built my "base" (had read something about the differences on "houses" and "bases", a house was free standing, a base used the terrain as part of the structure and was more ideal for a first night) into a hill, and then spent a whole lot of time collecting resources so I could make the walls creeper proof and unable to be blasted through. I think by the time I was done with everything, the walls were about 15 blocks thick and the inside was 4x4 with a mine going down out the back and into the hillside. I then built a giant pillar up out the top of my base because I wanted more space and figured creepers couldn't climb up a pillar, and then made a giant floating glass room about 50 blocks above the ground (I didn't know anything about sneaking, and it was about 10x10 expanding out from a 1x1 pillar, so as you'd imagine, I fell to my death A LOT). Then I explored, made some bases on top of and inside some pretty cool mountains, along with minecart rails connecting them (which didn't really work, because powered rails didn't exist at the time). Then the world got corrupted somehow and I lost all my stuff.
Time passed, I made a new world, and was sad.
A few months later, however, I got a mapping program (Minetographer, I think it was), and mapped my new world. Lo and behold, two different areas showed up on my world, one with my new base, and my old bases about 45 chunks of nothing away. I then spent an hour working my way back and was happy.
Never did get off of peaceful mode.
