A collection of cities and worlds to draw inspiration from or use outright for your own settings.
Assume, to be totally arbitrary, a council of thirteen archmages. Below them are seven circles of seven mages each, and below these are one hundred apprentice mages at various stages of learning. They are not permitted to learn the higher arts of magecraft until an opening appears in one of the seven circles (This may determine what learning they specialize in, if that’s what you’d like. One interesting ramification of this is that a chosen apprentice could potentially have to choose between entering into a school of magic which ze has no interest in, or passing up advancement this time around but risk never being chosen again).
A small group, honestly, but they are the nucleus of something more. To support this population you require additional people. Let’s say that every archmage has an average of three servants for general tasks, every full mage one servant, and that there is another servant for every four apprentice mages.
Now we have a bit more than 270 people. But wait, there’s more! All of these people still need to be supported, and the mages would like for the city to be self-sufficient. You need farmers, of course, but also a few specialists each in fields like cooking, carpentry, bookbinding, tailoring, and blacksmithing. You could easily set the population at three thousand or, for a self-sufficient town organized around meeting the needs of a magical elite. If you required the needs of their society, or added soldiers and guards (who increase other populations by dint of needing more weapons, more food, &c) then you can adjust the number upward. Likewise, if mages can create reasonably capable servants from magic then you can adjust some of the numbers down (unless they still need to eat, in which case keep all the farmers).
Before the world was, there existed the primordial Giant, which went by many names: Ymir, Leviathan, Uranus… Then the Giant was slain. Its jaws were torn apart to set the foundations of the world and its ceiling, and its blood poured out to be the sea and fertilize the soil, and its eyes were put into the sky to be lights. All this and more was done, and surely it is so.
And this is known. But what is a secret is that the veins of the Giant are still open, and to go through them is to tread strange paths. For there are other Giants, twins or all reflections of each other, and these too were slain and divided for the making of worlds. To travel the innermost roads of one is to find a way to the others, as if the worlds of these Giants were held within the first. But the wise know that this is not so, and that the Giant of our world may be reached as if it were within these others as surely as they may.
Thus we say that they are all reflections of each other, for none is more real than the rest and all are contained within the bowels of the others, even as they are contained within its own.
It isn’t hard to tweak the previous setting. Let’s take a world whose only land mass is a single, moderately-sized continent. Say, the size of Africa and Europe together. There are no islands past this, only a wide expanse of ocean.
But the ocean is a path to other worlds. It is possible to travel to the oceans of other worlds. One’s destination is determined by such things as the time and, most especially, the exact route. For this reason a knowledge of constellations is vital for proper navigation, because the necessary route mirrors a path drawn out between particular stars.
That city which is called Babilu-Ur, called Calakmul, called Rilex, a city whose infinite size is matched only by its bureaucracy. A young child could set out in one direction and, never wavering or turning away, die of old age before reaching an end to the city. If there is an end, then there is no one in these parts that has heard of it even in legend.
In this city, where districts can be hundreds of miles long, there is great variety. Some districts choose their governors by lot. Others according to bloodline. Some by the will of the people, or by a small number of the people. Some are governed by councils, others by individuals. They report to higher authorities, and so the chain of command goes.
The Ascendancy. The Authority. Central Directorate. These are a few of the names given to the semi-mythical capstone of the hierarchy, which some call the Hydra or the Machine. In truth, nobody knows if there is a master home at the asylum anymore, or even what that would mean in practice.
There are districts that have been long-abandoned, left desolate after one kind of disaster or another, plague or famine or war. There are districts that have been leveled by fire, rebuilt, leveled and rebuilt again. There are districts that have walled themselves away, declaring independence against the Machine. Some are successful. Some wither away or are overwhelmed by neighboring districts, to be subjugated or wiped out of existence.