Flipside Tower is the biggest structure in Flipside as well. When Tippi first brought Mario to Flipside, this is where they appeared. On the top of the tower, there are doors to other universes. To open a door to a new universe you must first put a Pure Heart in a Heart Pillar. There are a total of 7 doors on Flipside Tower. Like many locations in Flipside, this place too has a shadowy counterpart in Flopside. Flopside Tower, only when the final Pure Heard is placed in its pillar, has only one big dark door leading to Castle Bleck, the land where Count Bleck resides.
- The first door is red and it leads to Lineland.
- The second door is orange and it leads to Gloam Valley.
- The third door is yellow and it leads to the Bitlands.
- The fourth door is green and it leads to the vast reaches of Outer Space.
- The fifth door is pale blue and it leads to Crag.
- The sixth door is blue and it leads to Sammer's Kingdom.
- The seventh door is purple and it leads to the Underwhere/Overthere.