The Wonderful Adventures of Nils. by Selma Lagerlöf

In The Wonderful Adventures of Nils, Selma Lagerlöf tells the story of Nils Holgersson, a young boy who is transformed into an elf after a set of misdeeds. Escaping with his family's farm goose he joins up with a flock of wild geese and travels with them across Sweden as they return to their annual nesting grounds in Lapland. The story was originally written as a commission for the Swedish National Teachers' Association to write a geography book for children and has become a firm favourite in the country.
It's been adapted for screen many times, translated into over 30 languages and, until recently, was the artwork on the 20 krona banknote. Although originally published in English in two volumes-the second starting at "The Story of Karr and Grayskin"-here they are presented as a single combined story.