5 Dollars (Apollo 11 50th Anniversary)

The Apollo 11 $5 Gold Coin: a coin curved like the Moon's horizon

To mark fifty years since two men walked on the Moon, the U.S. Mint did something it had only done once before: it curved the coin. One face caves inward, the other bulges out — and on those two domed surfaces sit a bootprint pressed into lunar dust and the reflection caught in an astronaut's helmet.