A hole in the top of this tower fits Goku's Power Pole, which serves as the link between the tower and Kami's Lookout. It should be pointed that it is made of a quite durable material, that the structure itself is hard to destroy. Bora and the rest of his Native American tribe are located at the base of the tower as guardians as seen in Dragon Ball. The name "Karin-Tō" (カリン塔), is a pun on a type of fried dough cake called Karintō (花林糖). From Dragon Ball Wiki, a Wikia wiki.