Tower of Teeth
In a dimension formed by little kids' imagination, the Tooth Fairy's building is in a world that has blue sky above, green grass at your feet, and nothing in between, no horizon when you try to look into the distance. There are trees with really brown trunks, and flowers standing on the ground with exactly two leaves, one on each side.
The Tower itself is pure white, there are no windows and no lighting devices (lamps, torches, etc) in the building, but there is pure white light inside the Tower, casting no shadows. The original Tooth Fairy resided on top of this tower and operated his franchise of hiring young women to pay kids to legitimately obtain their teeth, so these teeth could be stored in a safe place (the Tower) where people with bad intentions should not be able to steal the teeth in order to cast magic on the children.