The first-ever crossword puzzle ran in the New York World newspaper on December 21, 1913.
One hundred years later, the puzzles are still extremely popular and run in newspapers across the country. The crosswords we see today are a bit different from the original "word-cross," which was in the shape of a diamond and didn't note "across" or down" moves.
See if you can solve the world's first crossword puzzle, embedded below:
Parade magazine has an answer key for the puzzle.
And if the above crossword is too puzzling, NPR has an updated version with some of the more obscure words removed.
Although New York World editor Arthur Wynne is credited as the inventor of the crossword puzzle, The Guardian points out that similar word games can be traced back as far as Pompeii.