"One of the biggest attractions of George R.R. Martin's high fantasy series A Song of Ice and Fire, and by extension its HBO television adaptation, Game of Thrones, is its claim to historical realism. The author, the directors and producers of the adaptation, and indeed the fans of the books and show, all lay claim to Westeros, its setting, as representative of an authentic medieval world. But how true are these claims? Is it possible to faithfully...