3 More Creations Meant to Last Forever

Finland's Onkalo nuclear waste disposal bunker is far from the only human invention intended to endure for millennia. Here are three more things built to stand the test of time.


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Randy Montoya

Le Grand K

"Le Grand K" is the nickname of the international standard kilogram, a cylinder of platinum-iridium alloy about the size of a film canister housed in an underground vault in Paris. Cast in 1879, Le Grand K is removed from its triple-bell-jar housing every 40 years so that the 40 copies held by other nations can be weighed against it.

The kilogram is the only standard unit still defined by a physical object. That's a problem, because Le Grand K appears to be losing mass—and, in a nice turn of phrase by Jonathon Keats, "by definition, any physical change to it alters the mass of everything in the cosmos." (That, and all units of measure derived from mass, including newtons, joules, and watts.) Efforts are underway to come up with an unalterable standard, but until that happens, we'll all slowly pack on micrograms.