Dome of Stars
The Dome of Stars refers to two great starred domes.
The first Dome of Stars was the Dome of Stars of Valinor, created by the Vala Varda (also known as Elbereth), and referred both to the great domed building in Valimar, as well as (poetically) the stars of the skies.
The second Dome of Stars was the great hall in the King's city of Osgiliath, capital of Gondor, which Elendil built on top of the great bridge across the Anduin, and where the chief Palantír was housed.
This second Dome of Stars was destroyed during the civil war of the Kin-strife.