Ketterlinus Gymnasium was named after philanthropist Elizabeth B. Ketterlinus, who donated the land on the corner of Mulvey and Orange Streets to the St. Johns County School Board. Ketterlinus was the daughter of William Warden, who built the nearby Castle Warden (today known as the Ripley’s Believe It or Not! Museum). In 1924, Ketterlinus High School opened, using Francis Field as their football field. After many changes, including a fire in 1981, the school became Ketterlinus Elementary in the 1990s and is still open today, across the street from the Gymnasium.