Long ago, the Netheril empire boasted a fleet of flying cities, housing an entire magocracy, infamous and terrifying. When the empire fell, it did so literally, great cities crashing to the ground in a cataclysmic event. One city however, was unaccounted for, because it had gone to explore a strange twist of planar geography - the land of Kantas. When it fell, it fell in the jungles of Harnash, and it changed the face of that society forever.

The city fell so precipitously that it landed almost perpendicularly - almost on its side. The remaining defenses of the city meant that it remained largely intact, in fact a magical barrier activated and persisted. To the locals of Harnash, they couldn't enter the city at all.

It took centuries - first to learn the Netherese language by spying street signs and menus with telescopes, piecing together meaning from a million scattered clues; then the understanding of their arcane language to find a way to pierces the barrier and explore the city itself. A base camp was established, and slowly the lower buildings of Gadenthor were converted into living quarters - albeit on their side.

Eventually, even the government found a place to reside in the ruined city, in a university high at the top of the ruin so they could survey the land in its grandeur.

Over the years Harnash learned much of magic and technology from these ruins. Notable technologies have included carbonated water and the thermometer. Not necessarily life-changing, but significant.

In Season 10: Ex Astris, Gadenthor returned to the skies only to be taken by Githyanki marauders, floating it off to the east. When the Dawnlands adventurers beat back the Githyanki, the city was returned to Harnash, now with far more of the magical systems that ran the city in the distant past active.

Exploration has resumed, with many different challenges facing them now. The city was more awake, more alive. Some paths that were well trodden were no longer safe while many others had opened up.