You know Valentine's Day is always on February 14th, but back in 400 A.D., it was February 15th.

The Fertility Festival had women put their names in an urn and bachelors would pick a name and be paired with her for a year.

All that stopped around 498 A.D. when a Pope declared February 14th St. Valentine’s Day.

Written Valentines didn't appear until after 1400. The oldest Valentine still in existence was written in 1415 by Charles, Duke of Orleans, to his wife while he was imprisoned in the Tower of London.

Fast forward to today where nearly 1 billion Valentine's Day cards are sent. That’s second only to Christmas at 2.6 billion.

In addition to the United States, Valentine's Day is celebrated in Canada, Mexico, France, Australia, Denmark, Italy and the United Kingdom.

You can thank a Brit for the traditional box of chocolates. The first Valentine's Day box of chocolates was introduced by Richard Cadbury in 1868.