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 4 months to create and used 2 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.