The Dome of Stars was a great domed hall in the city Osgiliath, the capital of Gondor, where the chief palantír, the Master Stone of Osgiliath was kept.
The Tower of the Dome of Osgiliath was destroyed during the civil war of the Kin-strife in the siege and Burning of Osgiliath and the palantír was lost in the river Anduin in T.A. 1437.