Flipside Tower is a white, monumental building in the center of Flipside, and the highest accessible floor in the town. It is either accessed via elevator from the second floor or by using the Return Pipe, and can act as a short-cut to the third floor if one chooses to jump off of it.
The purpose of the Flipside Tower is to allow individuals to travel to different worlds by accommodating Pure Heart Doorways. Each doorway is opened after a Pure Heart is placed into any empty Heart Pillar, either in Flipside or in Flopside. The tower offers seven doorways altogether for access.
The tower is in addition where Mario entered Flipside for the first time, and where he had he met Merlon. If the player chooses to continue his game after it has been beaten, he will start off on the tower.
Flipside Tower also has its own counterpart in Flopside: the Flopside Tower.