Royal Castle was a Miami, Florida-based hamburger restaurant chain known for its miniature hamburgers that are similar to White Castle's hamburgers, and its Birch Beer beverage, a version of root beer. It was founded in 1938 by William Singer, with an initial restaurant located at N.E. Second Avenue and 79th St., in Miami. Royal Castle eventually grew to 175 locations throughout Florida, Georgia, Ohio and Louisiana, with the bulk of them in Miami. One Royal Castle still exists in Miami, at 2700 NW 79th Street.