6. The World’s Only Complete Deck of 15th Century Playing Cards is in the Cloisters 

Image from The Metropolitan Museum of Art via Wikimedia Commons

You can find the world’s only (known) deck of playing cards from the 15th century located inside gallery 13 of the Cloisters. The set is comprised of 52 cards, made from four layers of pasteboard, decorated using pen, ink, opaque paint and glazes. Like modern decks, it is comprised of four suits (hunting horns, dog collars, hound tethers, and game nooses). However, its condition suggest that they were rarely (or never) used.