Some trace Valentine’s Day origins to a Christian effort to replace a pagan fertility festival that has been dated as far back as the 6th century B.C. During the festival of Lupercalia, Roman priests would sacrifice goats and dogs and use their blood-soaked hides to slap women on the streets, as a fertility blessing. According to legend, women would later put their names in an urn and be selected to be paired with a man for a year.

Every year, thousands of romantics send letters addressed to Verona, Italy to “Juliet,” the subject of the timeless romantic tragedy, “Romeo and Juliet.” The city marks the location of the Shakespearean tale, and the letters that reach the city are dutifully answered by a team of volunteers from the Juliet Club. Each year, on Valentine's Day, the club awards the "Cara Giulietta" ("Dear Juliet") prize to the author of the most touching love letter.

The Valentine’s Day tradition of giving a box of candy was started in the 19th century by Richard Cadbury, a scion of a British chocolate manufacturing family. With a new technique recently established at the company to create more varieties of chocolate, Cadbury pounced on the opportunity to sell the chocolates as part of the beloved holiday.

Some accounts claims history’s first valentine was written in perhaps one of the most unromantic places conceivable: a prison. Charles, Duke of Orleans allegedly wrote the love letter to his second wife at the age of 21 while captured at the Battle of Agincourt. However, the British Library contends the letter, which was actually a love poem, dates to the period when Charles had returned from England to France. So, according to the British Library, it was likely not composed from his prison cell.

During the Victoria Era, those who didn’t want the attention of certain suitors would anonymously send “vinegar valentines." These cards, also called penny dreadfuls, were the antithesis of customary valentines, comically insulting and rejecting unwanted admirers. They were later used to target suffragettes in the late 19th and early 20th century.

The term “wearing your heart on your sleeve” may have origins in picking a valentine. Smithsonian reports that during the Middle Ages, men would draw the names of women who they would be coupled with for the upcoming year while attending a Roman festival honoring Juno. After choosing, the men wore the names on their sleeves to show their bond during the festivities.

The iconic chalky heart-shaped candies that have been passed out lovingly every Valentine’s Day started out as lozenges. According to the Food Business News, pharmacist and inventor Oliver Chase created a machine that would quickly create the lozenges before switching to using the machine to create candy—later known as Necco Wafers.

Chase’s brother came up with the idea to print messages on the candy in 1866, and the candies got their heart shape in 1901, appealing specifically to Valentine’s Day sweethearts.

The chubby baby with wings and a bow and arrow that we call Cupid has been associated with Valentine’s Day for centuries. However, before he was renamed Cupid, he was known to the ancient Greeks as Eros, the god of love. Eros, the son of Greek goddess Aphrodite, would use two sets of arrows—one for love and another for hate—to play with the emotions of his targets. It wasn’t until stories of his mischief were told by Romans that he adopted the childlike appearance that we recognize today.

The idea of using a kiss to sign off on valentines also has a long history, according to the Washington Post. The use of “X” came to represent Christianity, or the cross, in the Middle Ages. During the same time, the symbol was used to sign off on documents. After marking with an X, the writer would often kiss the mark as a sign of their oath. As the gesture grew among kings and commoners to certify books, letters and paperwork, these records were described as having been “sealed with a kiss.”