La Caseta Magica (The Phantom Tollbooth)

This book was surprisingly fun. It is very much in the Narnia / Alice in Wonderland / Pinnocchio tradition of child goes on weird and random adventure to a new world. But this one managed to be weird and wild like Alice/Pinnocchio but having a similar level of an actual story as Narnia. Very clever puns throughout and fun personifications of math and english.