Twenty years ago an amateur diver discovered an ancient shipwreck off the coast of Sardinia. It was filled with Roman lead ingots. In an ironic historical twist, those lead ingots are more valuable than gold for a scientific purpose.
Lead itself is a great wall because it's so heavy that it shields almost everything out. But freshly mined lead isn't entirely radioactively silent: it has radioactive isotopes in it that emit radiation that confuses scientific detectors. Because these old ingots were left to decay for thousands of years at the bottom of the sea, all the unstable lead in them has already decayed, and they are radioactively inert. Now they're being sent to scientists who are going to melt them down and build lead walls for their detectors -- silent walls that won't produce even the faintest whisper of radiation so the detectors can listen for neutrinos in peace.
Bet the people two thousand years ago who forged those ingots never suspected that they were actually participating in a scientific experiment! Hoepfully they'll get some kind of co-authorship ... or at least an acknowledgement.
More info here.