One of my childhood favourites… everytime I read this it gets better.

The Magician’s Nephew by C.S. Lewis (Chronicles of Narnia #1)
The Lion, the Witch and the Wardrobe by C.S. Lewis (Chronicles of Narnia #2)
The Horse and his Boy by C.S. Lewis (Chronicles of Narnia #3)
Prince Caspian by C.S. Lewis (Chronicles of Narnia #4)