The Dwarves' vault contains many of the dwarves greatest treasures and technology including the Running Water Root, Burning Mirror and Firewind Cannon. It is located to the north of the Village of the Dwarves because it was too large to build within the village.
The vault was infiltrated by Kage who stole the plans for the Burning Mirror, delivering them to Kwanda Rosman. Despite this, the Chief of the Dwarves did not believe the vault could be infiltrated by "sluggish" humans and challenged McDohl and his entourage to steal the Running Water Root from within to verify their story.
When the party succeeded, the Chief of the Dwarves grudgingly built the Firewind Cannon to combat Kwanda's mirror. Following the Gate Rune War, Rock was hired to design a new safe for the dwarves, suggesting that the numerous infiltrations during the war brought doubt on the vault's security.
Along with the above treasures, it is also rumored that the vault holds a weapon to be used only at the end of the world, secure in a part of the vault called "the center of the center of the vault". It is unknown if this is true or a result of the tendency of dwarves to exaggerate, however.