AUSTRIA: Due to salt’s invaluable use in food preservation and seasoning, humans have been extracting it from underground mines for millennia. A recent discovery of a child’s shoe from the Hallein Salt Mine in the village of Dürrnberg revealed that even young children toiled away at this endeavor. The remarkably well-preserved leather shoe dates to the second century B.C. It contains evidence of flax or linen laces and is equivalent to a modern U.S. child’s size 12.5.