| Opaline Vault
|| The Rainbow Metropolis
|| Peerless Empire, Plane of Earth
|| 2,280,000 Shaitans, 1,825,000 mephits, 675,000 earth wysps, 450,000 earth elementals, 300,000 dwarves, 150,000 oreads, 100,000 humans, 80,000 elves, 80,000 jann, 60,000 other
|| Lawful neutral
|| Sultana Ashadieeyah bint Khalid
Source: Planes of Power, pg(s). 27-28
The Opaline Vault is the centre of the shaitan Peerless Empire, and the seat of power of Sultana Ashadieeyah bint Khalid, ruler of the shaitan race.
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.
Paizo published a major article about the Opaline Vault in the Plane of Earth chapter of Planes of Power.