The Enchanted Castle - Edith Nesbit - Bog

Once upon a time, there were three bored but imaginative little children, Jerry, Jimmy, and Cathy, left all alone in a boarding school with one nosy maid and an agreeable French governess for the holidays. Having securely wrapped the governess around their collective little fingers, they secure her permission to go into the woods one afternoon. In the woods, they find a castle garden, and in the garden they find a sleeping princess dressed all in pink silk with a magic ring on her finger.

The princess is really Mabel, the housekeeper's niece, who is only pretending to be royalty. But when she shows them a secret room filled with treasure where they discover a magical ring, enchantment becomes a reality.

Be careful what you wish for. There is invisibility, there are secret passages, there are gods and goddesses and a dinosaurus, there is magic and myth and a whole world of hidden secrets.