Officially, this is the World's First Crossword Puzzle. Originally appeared in the New York World newspaper on December 21, 1913. It's author, Arthur Wynne, called it a "Word-Cross" puzzle. His clue numbering didn't separate ACROSS and DOWN clues, so it has been changed to the modern standards on this page. You can read more about this puzzle here.
Click on any square to see the clues for words crossing it. Type in a letter to fill the square, use Space Bar or BackSpace to clear it. Click in the current (highlighted) grid cell to change directions.