Pays to keep a low profile.

One of the more bizarre predictions to come out of Einstein's general theory of relativity is that the higher above sea-level you go (strictly, the further you are away from the centre of the Earth), the faster time passes.  But thanks to two extremely, extremely accurate atomic clocks this has now been shown to be true - even though the clocks were positioned with one just a foot higher than the other, the higher one ran faster, albeit infinitesimally, than the other.  This of course means that if you live on the top floor of a tower block, you age faster than someone living at ground level!