Dimmsdale is the largest city in The Fairly OddParents universe that provides the central setting for the Nickelodeon animated series The Fairly OddParents. Dimmsdale is a parody of Hollywood, California. It is located in California, though its exact geological location in the state differs in certain episodes, which Timmy Turner lives there.
Dimmsdale is the third dimension you visit in Nicktoons Unite!. However you don't actually play in Dimmsdale, as you only enter Crocker's Fortress. You have to go through the fortress to go to the middle to the rainbow. Once there you must put a few prisms in a correct way so Cosmo and Wanda can teleport you to the Fairy World.
In the handheld version however, you do go through the city of Dimmsdale.