Ganon's Castle is a location from The Legend of Zelda: Ocarina of Time. The castle is located North of Hyrule Castle Town and is home to the last dungeon in the game, Inside Ganon's Castle, which floats in the middle of a lava pit.
The area is the ruins of Hyrule Castle after its takeover by Ganondorf. A single Gold Skulltula can be found on the remnants of the Hyrule Castle's gate. Also in the area is a Great Fairy Fountain, the same location of the Fairy Fountain where Link learned Din's Fire. In order to access it, however, Link must have acquired the Golden Gauntlets from the Shadow Barrier section of Inside Ganon's Castle. The Great Fairy of Courage inside enhances Link's defense.
Shigeru Miyamoto has said that in his original envisioning of Ocarina of Time, the entire game would take place in Ganon's Castle, similar to the design style of Super Mario 64; he said he imagined specifically a dark meadow or an ocean in different rooms.