It's not in any region and can be entered by using the Teleporting Item which you get after completing Myotismon Quest.
Digimon Living Here:
ExVeemon (LV 52)
ExVeemon (LV 54)
ExVeemon (LV 56)
Wizardmon (LV 52)
Wizardmon (LV 54)
Wizardmon (LV 56)
