The Castle of Iron is the title of a fantasy novella by American authors L. Sprague de Camp and Fletcher Pratt, and of the novel into which it was later expanded by the same authors. It was the third story (and afterwards the second volume) in their Harold Shea series. As a 35,000-word novella it was first published in the fantasy magazine Unknown for April, 1941. The revised and expanded novel version was first published in hardcover by Gnome Press in 1950, and in paperback by Pyramid Books in 1962. The book has been reprinted by a number of other publishers since its first appearance. An e-book edition was published by Gollancz's SF Gateway imprint on September 29, 2011 as part of a general release of de Camp's works in electronic form. The novel has been combined with other books in the series in the omnibus editions The Compleat Enchanter (1975), The Complete Compleat Enchanter (1989) and The Mathematics of Magic: The Enchanter Stories of L. Sprague de Camp and Fletcher Pratt (2007). It has also been translated into Italian. The Harold Shea stories are parallel world tales in which universes where magic works coexist with our own, and in which those based on the mythologies, legends, and literary fantasies of our world and can be reached by aligning one's mind to them by a system of symbolic logic. In The Castle of Iron, the authors' protagonist Harold Shea visits two such worlds, first (briefly) that of Samuel Taylor Coleridge's poem "Kubla Khan" and second that of Ludovico Ariosto's epic, the Orlando Furioso. Source: Wikipedia (en)