I started in Alpha v1.1.2_01, roughly sometime in September 2010.
I built a home was on top of a mountain, but got tired of keep going up and down said mountain for resources, so built stairs. Instead of building outside of the mountain though, the stairs it actually went into it. The stairs became so long I nicknamed them the "Stairway - to HELL." I vaguely remember coming out the side of the mountain (Still very high up) and having to try and decide what to do next. I think I double-backed and went back into the mountain in the opposite direction from the end of the first set of stairs. (I think..)
I do not have this world anymore however and the only picture is that of the stairs going into the mountain, and even then it has the menu screen over it because the game was paused.