Yep, I actually am working on some of the locations. Well, I forgot for a little bit, but I'm back on it now. For today: New Atero.My biggest thing with New Atero was trying to realistically explain why a source of water, a rainforest requiring a lot of water, and a desert, which requires a lack of water, are so close together. My solution, as it tends to end up, was including a mountain.
This mountain ridge, the tail end of a range going off to the northwest, sort of divides the city in half. On one side is Ga- and Le-Magna, while on the other is Po- and Onu-Magna. Ko- and Ta-Magna straddle the ridge itself. Av-Kini, the Temple of Light, sits on a small peak in just about the center of the city.
The idea is that winds blow from southeast to northwest off of the Great Bay. This brings it across the central range, where most of it gets caught and ends up running back down the same side of the mountain. Consequently, the southeast slope of the ridge is a rainforest, while the northwest side has become a desert due to the minimal rainfall. Occasionally the clouds make it high enough to snow among the Ko-Magnan knowledge towers.
While this explains most of the city's districts, it does not explain why Ta- and Onu-Magna are where they are. As for the former, geothermal vents and geysers on the far tail of the ridge made the region a bad choice for most things. Fortunately it was a great choice for an industrial district full of heat-resistant individuals. The natural heat is also a perk for things such as smelting or processing ores, giving the heating process a natural boost.
Onu-Magna, meanwhile, exists because of the natural caves going through the ridge. They would have taken both sides of the mountain, but the plantlife and air Matoran wanted their rainforest. So the Onu-Matoran began digging in the caves, while the De- and Ce-Matoran constructed the Archives on the surface.
The orientation of all of this is important, too. The placement of Po-Magna to the west/northwest is very deliberate; it's the beginning of the Wastes, which stretch most of the way west to the Dark Ocean. (More on that later.) What is important about the wastes is that it's where the Fortress of Darkness once was (until Solorok did his remodelling into the Fortrex of Darkness). It makes sense for the Empire to keep attacking the stone district: it's closest.
However, this does raise some holes in other worldbuilding, mostly concerning Le-Magna. Early in the story, there was an Imperial assualt on Le-Magna. Why go all the way over there? Also, at the beginning of the New World, I stated that one of the main train stations was in Le-Magna. This makes sense in terms of past landscapes, where the air matoran have been in charge of transportation, but absolutely no sense when it comes to the layout I have.
As always, thoughts are appreciated.