Brightlord Skybreaker

I don't think that the whole shattered plains was a city but maybe central portions of it. I've always thought that it was the ruins of Urithiru or some 'gateway' town through which you pass to Urithiru and that it was destroyed either by the spren after the oathpact was broken or by some malevolent force that wanted to erase any trace of Urithiru from the map. The way they describe the destruction radiating from the centre of the plains in WoK always makes me think of a meteor or super powerful radiant smiting the centre of the city to demolish it.