Castle Greyhawk is the seminal megadungeon of Gary, the New World, the fortress that encompasses “the wizards of the order”. It stands on the Material Plane of Oerth; its lower levels descend to the Underdark and open portals to the Elemental Plane of Earth.
The gesta (campaign-cycle) of Gary takes this castle as its central setting.
See also
- Gary, the New World
- Tentacled Creature (New World), a creature recorded in the same gesta cycle
- Les Libertateurs, a faction active in this setting
- The Columns