Actually the Royal Castle legacy lives on in Miami FL, where the company started sometime around 1938. One of the early (1939) stores sufferred a fire in recent years, but is scheduled to reopen soon, while another has been operating successfully. This is all that is left of a chain that stretched across the southeastern US and to my mind, was superior to the White Castles or Krystals. Three burgers and a birch beer in a frosted mug for all of $.35 was my treat every Saturday before attending the kid’s movie program at the Rosetta Theater in Little River, a suburb of Miami.
Royal Castle reached way beyond the Southeast. Royal Castles were very big in the midwest — at least in Ohio, and that last two I know of in Ohio were right off Interstate 71 at Sunbury and at Lodi. The first Royal Castle I ever saw, and enjoyed, was on Biscayne Boulevard in Miami back in 1951 or 1952.