From A Wiki of Ice and Fire
Oros is a ruined city that sits on the northern coast of the Smoking Sea, that was said to be second only in majesty to the city of Valyria before the doom. It lies to the south of the Lands of the Long Summer, is connected by Valyrian road to Mantarys, while across the Smoking Sea lies Tyria. The ruins of Oros are still inhabited to some extent, although it is not clear whether by descendants of its original inhabitants. The few stories told of these latter day dwellers tend to be dark.