Coin collecting, also known more broadly as numismatics, has been going on for thousands of years. In fact, there's evidence that it took place in Ancient Rome. So it's perhaps no surprise that, to appeal to this collectors' market, mints and treasuries around the world have started producing unusual coins in limited quantities.
These coins often feature unique properties and innovative touches not commonly associated with regular currency, which could increase a coin's desirability in the eyes of numismatists. Here are 10 examples of the coolest and most unusual coins in the world.
