639 years? Big deal, The Long Now foundation built a clock to last 10,000 years. I hate John Cage since I got his massive world-wide hit 4′33″ stuck in my head.
replies(5):
The Long Now Foundation is attempting to build a clock to last 10,000 years.
Construction began close to a decade ago, and there is no estimated completion date. Construction of the clock may well last 10,000 years.