Dragonstone is a volcanic island at the mouth of Blackwater Bay, created by the active volcano, Dragonmont. Damp and dreary, it smells of sulfur and brimstone. Castle Dragonstone is a grim place, the castle was built using by the Valyrians, using arcane arts, fire, and sorcery. Two major walls protect the central keep. It is made of the titular dragonstone, making it immune to dragonfire.