The Magical Worlds of Narnia

From the back cover:

... The Magical Worlds of Narnia explores the myths, legends, and history behind Lewis's beloved Narnia series. Discover the medieval lore and ancient myths that inspired Lewis, and trace Narnia's origins to the Bible, the tales of King Arthur, and various corners of history. This is a passport to the undiscovered corners of Narnia--and the essential guide to one of the most wondrous adventures of all time.