Leaning Tower of Pisa

The Leaning Tower of Pisa is a famous tower in Pisa, Italy that is known for its lean to one side. It has been referenced multiple times in the Arthur franchise:
 * In "The World Record," when Buster imagines walking around the world backwards, he fantasizes going past the tower.
 * In "Ants in Arthur's Pants," after Galileo is mentioned, a cartoon version of Galileo is seen dropping balls from the tower.