It is built on the inner surfaces of a 30-mile crystal geode, and is the largest settlement in the Plane of Earth. Buildings rise from the floor, walls, and ceilings, linked by bridges of bronze and steel. The light of countless glowing spheres is reflected and refracted many times by the surfaces of the geode, creating an unforgettable sight.2
Paizo published a major article about the Opaline Vault in the Plane of Earth chapter of Planes of Power.
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