For something that pretty much rules most of our lives, we actually know very little about money. You can learn more with a visit to the Money Museum. Run by the American Numismatic Association, the multi-level museum features over 250,000 monetary objects, a permanent exhibit on the history of money, an interactive gallery of American gold coins, experimental pattern coins, and paper money, a minting gallery, and a rotating gallery, currently exploring the money of the Civil War. As you might expect, you'll have to add to their collection with common currency in order to visit.