Mad Spire is, as the name implies a spiral structure, 720 feet tall (219.4 meters) and is 1850 feet (563.8 meters) across at it's widest point. Some areas of the spire overlap, forming shaded network of caves. Buildings are constructed on the rising incline areas and within the large caves beside them. Some parts of Mad Spire never see sunlight due to the dense collection of buildings obstructing sunlight from within these caves.
Between the levels in the cliff face are various carvings. Some of human nature, some much older and alien. Some individuals make home in the smaller cave structures in the sides that go further into the rock exoskeleton of the living city. Many of these are home to ancient terrors yet to be discovered.
Nearly two hundred years ago a number of intense threats led to the tribes of the area to form an alliance to survive. The details seem lost, though the tribes built a society together in the ancient ruins of a Serpent Man city.
When the major threat to the various tribes passed, many of the people moved on to their usual distant paranoid village lives. However many stayed and to this day fight for control of the city.
Mad Spire serves as a trade hub for the known world and for characters of different tribes of man to meet up. This of course still does not mean the characters will trust or like each other.
It didn't take long after settling that the tribes learned the city itself was alive, as it slowly began to open mouth pits to consume houses and people. This would have driven off the population had they not learned that these mouths only existed in certain locations on the city. The people began to use these pits as ways of disposing of waste, dead bodies and criminals. Over the decades the city has improved in appearance as it's health continues to grow from being actively fed.
The pit mouths have unusual alchemical properties that Alchemists and Sorcerers may find useful, if they can extract samples without being eaten alive.
Another trait of the pit mouths are that they release a smell that tricks those who smell it into thinking something favorable exists nearby. This is how it used to lead prey to it for consumption. For the inhabitants of Mad Spire, this feature makes for the most pleasant smelling of garbage dumps. This can also lead new arrivals to the city to unfortunate accidents...
The living city also has another positive feature. It pumps up water from underground and out of "springs". Most these are very small, though there are five major springs that flow out and form water falls and provides for a nice oasis surrounding the city.
The city is currently ruled by a Sorcerer named Raxsust Krad'toumn. He has ruled for nearly 130 years and seems not to age. This may be an illusion though. Over time he and his minions have gained access to a wide variety of Zeta (Space Alien) technology, including a few vehicles they have managed to learn how to pilot and numerous reprogrammed robots. Part of this advantage is that Raxsust recruits people who have escaped from Zeta run arcology cities and other areas that Zeta's oversee human populations. Many of these people have experience with the language and technologies, which of course makes them useful. It is also believed he has given a number of Zeta irrationalists safe haven in exchange for knowledge.
Over population, criminals and other undesirables are dealt with by Lord Krad'toumn by capturing and selling these individuals off as slaves. Some are sold in markets to caravan traders, while the rest are sold directly to Moon-Beast slavers. (more details on this at a future point.)
Mad Spire has no King! It is considered blasphemous to say anyone is actually King of the city. Lord Kard'toumn publicly executes anyone who refers to him as "King".
This may be superstition, though Lord Kard'toumn has declared "There is no King but the King who dwells in Carcosa" (in reference to the city of Carcosa). Most speculate that this has been the only reason Mad Spire has existed as long as it has without falling to the Avatar of Hastur.
Though it is not only illegal to declare anyone king in the city (even in jest), the locals will react in terror to anyone declaring such a thing and mob up and kill the one who spoke such. Claims of people speaking such things has led to many a "Witch Hunt" in the city.
Mad Spire has it's own minted coins. This is rare in the world of Carcosa. For my campaign the Mad Spire silver piece is the trade standard for equipment. Though most villages will use barter/trade instead of currency.
Numerous tribal gangs fight for control over sections of the city. Lord Kard'toumn tolerates this as long as the farmer's gardens are not destroyed, the water ways are not poisoned and the major roads are not blocked. When this happens, or the wars get out of hand, he sends in his minions armed with Zeta weapons and ends the conflict.
Work in Progress for the 1st Elevation section of the Mad Spire map: