Timekeeping on a grand scale – the 10,000 Year Clock

Timekeeping on a grand scale – the 10,000 Year Clock: "When we hear about things being built to last, we usually think in terms of years or decades ... or maybe, centuries. But millennia? Well yes, if you're talking about the 10,000 Year Clock. As its name implies, the 200 foot (61 meter)-tall timepiece is intended to run for 10,000 years, in a remote cave in West Texas."