The Wyrmberg was an upside-down mountain where the dragonriders lived alongside their imaginary dragons. It was also the home of Liessa Dragonlady, Greicha the First of The Wyrmberg, Lio!rt Dragonlord, K!sdra, and Liartes. It was visited by Rincewind the Wizzard, Twoflower, the Discworld's first tourist and Hrun the Barbarian during an expedition across The (Unnamed) Continent. Rincewind and Hrun were both challenged to combat. This appears to be a reference to Anne McCaffrey's classic novel 'Drangonriders of Pern' in terms of the dragon riders' relationship with their dragons, their naming style and the hierarchy of the Wyrmberg (led by a dominant female).
The Roosting Hall -This roosting hall where the Dragons lived was visited by Twoflower while riding on Ninereeds the Dragon's back after escaping the Dungeon where he and Hrun were imprisoned. The Dragons in here hung upside down by gasping onto metal rings with their talons and riders could move around upside down using special hooked boots attaching to small ceiling rings, almost like a heavy duty velcro.
The Dungeon - This is where Twoflower and Hrun were imprisoned and where he thought up Ninereeds the Dragon.