A castle in the air is a daydream or fantasy. Castle in the Air may refer to: Castle in the Air (play), a 1949 play by Alan Melville Castle in the Air (film), a 1952 British comedy film based on the play Castle in the Air (novel), a 1990 young adult fantasy novel by Diana Wynne Jones the Castle in the Air, in the children's book The Phantom Tollbooth, where the princesses of Rhyme and Reason are banished See also Castles in the Air (disambiguation) Castle in the sky (disambiguation)