Being a big fan of history and technology, I was amazed to come across this in Wikipedia:
This is one of the most clever stories I've ever heard out of WWII, the perfect blend of a scientist solving a tough problem with tools at hand.
When Germany invaded Denmark in World War II, the Hungarian chemist George de Hevesy dissolved the gold Nobel Prizes of Max von Laue and James Franck into aqua regia to prevent the Nazis from stealing them.
He placed the resulting solution on a shelf in his laboratory at the Niels Bohr Institute. It was subsequently ignored by the Nazis who thought the jar—one of perhaps hundreds on the shelving—contained common chemicals.
After the war, de Hevesy returned to find the solution undisturbed and precipitated the gold out of the acid. The gold was returned to the Royal Swedish Academy of Sciences and the Nobel Foundation who recast and presented the medals to Laue and Franck.
There's also a thread on Hacker's News with some interesting comments (and tangential discussions).