Qarth

The greatest city that ever was or will be, by its own account, sitting on the straits where two seas meet.

The fuller tale

Qarth grew where the Jade Gates join the Summer Sea to the Jade Sea, which is to say on top of a toll booth between two halves of the world. Three walls, thirteen milk-white towers, and the whole trade of the east passing through: it did not need to conquer anything and never seriously tried.

Its power is held by three groups who dislike each other in a stable way ÔÇö the Pureborn, the Thirteen, and the Tourmaline Brotherhood ÔÇö and its warlocks were once genuinely feared and are, by the time this chronicle reaches them, mostly a smell of dust and a very good trick.

The city is famous for its manners, its silks and its capacity to be perfectly polite while declining to help you.

The ground they held

 See the world in 298 AC on the timeline 

What became of it ÔÇö if an ending is written, it is here. Spoilers.

The chronicle records no ending here ÔÇö or none the maesters have set down.