The castle is reputed to be the largest Hollywood set built for any silent movie. Lloyd Wright, Frank Lloyd Wright's son, designed at least one set which he later remodeled as a temporary band shell for the Hollywood Bowl.
The 2008 book "Douglas Fairbanks" by Jeffrey Vance (page 151) debunks the myth that this was somehow "lost" for decades. It was never lost. In fact, the Museum of Modern Art has made it available through its Circulating Film Library (non-theatrical/educational distribution) since 1938.
The film was restored by the George Eastman House and the Museum of Modern Art in 2009 and was showcased with important screenings at the Eastman House's Dryden Theater (accompanied by an 11-piece orchestra conducted by Gillian Anderson) on October 24, 2009, and at the Academy of Motion Picture Arts and Sciences' Samuel Goldwyn Theater (introduced by author Jeffrey Vance) on June 27, 2011.
"Just an Old Love Song", the theme song from the original score with music by Victor Schertzinger and lyrics by Sid Grauman was published to promote the picture."The Robin Hood March" was also extracted from the score and published by Chappell, 1923.
The cost of the film has been guessed at for decades. Jeffrey Vance (author of "Douglas Fairbanks", published in 2008) unearthed definitive production figures for the film that shows it had an actual production cost of $930,042.78.