Aerathain City, on the other side of the continent, 3rd Floor.
3rd Floor of the Tower was enormous, and thus as the logic should dictate, it should contain a lot of different biomes and environments. However, unexpectedly or expectedly, it didn't really happen because of the Nesser Dynasty, who terraformed the entire 3rd Floor to be one single biome.
Aerathain City was a one-time peculiarity on the 3rd Floor; it was initially the capital of some nation located in the Lower World. That Lower World was on the verge of becoming a Mana-Less World in a few millennia as Mana was dissipating from the World at an alarming rate.
Once, when some powerful Transcendent was bored, he transported the entire Aerathain City to the Tower and placed it on the 3rd Floor. Indeed, boredom could be dangerous for people who live a very long life.
Not like things like this happened often... not absolutely like this.
But that was not a real problem.
