Dark Origins: Valentine's Day.

The next time you have to work on a project for Valentine's Day, you may or may not want to reference this.

Check out this little primer on the dark, bloody and muddled origins of this cherished Hallmark holiday, courtesy of NPR.

A drawing depicts the death of St. Valentine — one of them, anyway. The Romans executed two men by that name on Feb. 14 of different years in the 3rd century A.D. (per Getty Images / NPR)