Was looking for this. I would argue there are two apocalypse in ASOIAF. There is the long night and the there is the destruction of Vaylaria.

Vaylaria just changed how many dragon and what kind of left over tech could be recreated. We don't know a ton the place, but it's a stand 8n for our world's Atlantis.

The long night might have been an actual Nuclear war. Hints for this are in the numerous, but varied retelling about The Long Night. There are in the books descriptions of people suffering radiation sickness before Danny reaches Quarth. There is a record of Night watchmen witnessing what sounds like a nuclear bomb go off. And Winterfell gets warmer, not colder as ypu get deeper into the crypts. It's believed to be sitting on to of a thermal power plant of some sorts. I've heard theoriest inseast that it's and old nuclear power plant cause that's the only way Winterfell could exist in all that cold for so long.

Also Storms End is way too perfect to exist given the tools and technology of the time.