The Inverted Tower is a structure that serves as a vault for the hidden artifact at Fablehaven. Located in theRevenant's Grove, the entrance to the tower lies in the middle of a clearing where stands a sizable, raised platform of reddish stone flecked with black and gold. At the center of this spacious platform is a round socket surrounded by multiple circular grooves that radiate out like the rings around a bull's eye. To gain access, a key must be inserted into the socket. Once the key is in place, the outer rings drop away one at a time, until a conical stsircase is formed, which leads down to a chamber.
This first chamber of three is not much larger than the widest ring of stone, its floor a single slab of bedrock. There is nothing in the chamber except a pair of doors at opposite ends. One section of the chamber's wall is covered in writings in various languages, including a few repeated messages in English and fairy languages. Behind both doors are false staircases. Along the wall is an invisible entrance with a genuine set of stair leading to the next chamber. The second chamber is large and circular. White stones set in the domed ceiling provide illumination. Deep, golden sand-some of which is quicksand-covers the floor. Monsters are depicted on the walls of this chamber- a blue woman with six arms and the body of a serpent, a Minotaur, a huge Cyclops, a dark man who appears human from the waist up but has the body and legs of a spider, an armored snakelike man wearing an elaborate headdress, and a Dwarf in a hooded cloak. Each figure has a key around its neck. On the far side of the room is a door painted on the wall. When touched, the painting becomes an actual door, but it's locked. One of the monsters' keys will open the door, but all of the monsters also become real when touched. Defeat a monster to obtain a key.
Once the correct key is used, the door will open to reveal another stairway that descends to the third chamber. On the floor is a complex mosaic depicting primates engaged in an enormous battle in tall trees. The mosaic's perspective is from the ground looking up and creates a disorienting effect. The instant the chamber is entered, the primates come to life, frenzied beasts intent on killing.
Once the apes are defeated, however, a passageway on the opposite side of the room opens to yet another stairway, which in turn opens to the fourth and final room, where a glass, Black Cat Guardian sits atop of a pedestal, a key hanging around the feline's neck. Once the Guardian is defeated, the hidden artifact will be revealed.