It's rare that two of the biggest nerd holidays fall on the same day; so to celebrate the momentous occasion, every library in the city of San Diego will be hosting a "showdown."

Saturday's "Super Hero Sci-Fi Showdown" is the perfect photo opportunity for both superhero fans taking part in Free Comic Book Day and Star Wars fans celebrating their annual holiday, "May the 4th be With You."

Attendees are encouraged to head to one of the city's 36 libraries dressed up as their favorite superhero or Star Wars character for a match-up of epic proportions; at noon, the two camps will "battle" to see which side has the most representation.

Everyone who participates in the event (and even those who don't) ends up a winner, though -- it is Free Comic Book Day, after all. Each library will be handing out one of two IDW Publishing comic books to attendees.

To find one of the three dozen libraries participating in the showdown, click here.

Free Comic Book Day began in 2002 when thousands of comic book shops gave away free copies of a variety of comics to encourage interest in the artform.

Dozens of shops across the county are participating in this year's event. Find a location near you here and find out what types of comics you may find here.

The San Diego Public Library system also has a stock of tens of thousands of graphic novels and comics that enthusiasts can check out year-round.

May the 4th be With You was started entirely by Star Wars fans and was an unofficial holiday until Lucasfilm hopped on board in recent years.

Last week, Star Wars Day became an official holiday in California when the state legislature voted to recognize the day. The move was meant to pay tribute to Star Wars: Galaxy's Edge set to open at Disneyland Resort later this month.