Not strictly a building as such, more a box within a building, but rather than start another sub-blog called Loo No 1-2-3-4 etc, I'll put it into the buildings one.
So . . . 42, other than Dear Douglas Adam's reference to the meaning of life the universe and everything, our loo.
When I was about seven it occurred to me that keeping a record of every loo that you sat (or stood in) would be quite interesting: the ultimate life-time conceptual art piece. But the idea became overtaken with a diary of tea shops instead (now lost, sadly). I suppose it's the fact that you inhabit these small spaces alone (unless one of those bizarre bench with holes type ones which exist on medieval bridges) with just your own bodily sounds and thoughts for company - excepting all the noisy airport/ restaurant/bus station etc loos one might sit in; but you are still in a cubical, on your own for a few minutes or seconds depending on the type of ablution you are undertaking . . .
This is our loo, snapped by a lovely Danish B and B'er and his fish-eye lens who stayed with us a couple of weeks ago. The small rectangular space is a shrine to 1975, the year our house was constructed, featuring: Star Trek, Mud, David Bowie, strange puddings from a book, interior decor of the moment, YFO spottings, and of course, wonderful-terrible fashion from that era of orange and purple.