The Astronomical Clock in Prague's Old Square displays not only time but sunrise, sunset, zodiac, mean revolutions of the moon and a whole bunch of other crazy stuff. It recently celebrated its 600th birthday with this incredible projected light show.
According to a commenter at BoingBoing, the projection took four months to create and used two Christie 18K HD projectors - that's 5000x1200 resolution.
The projection mapping was done by Michal Kotek and Lukáš Duběda at The Macula, with sound design by data-live, and production by Tomato Production. And while the projection is pretty insane, the clock itself, which has over 20 functions, might be even crazier.