The hub in which the majority of Aethervane adventures begin and end is Bleak Haven. It is a town built on top of a colossal skeletal humanoid skull and torso—that of a former god—which is adrift in the Astral Plane.
As a whole, the town is rather cold, dark, and dingy. The dim ambient light of the Astral Plane never provides more illumination than a moonlit night. Lampposts provide a bit of extra light to see by along the main drags, but the smaller alleyways are hidden in perpetual shadow. Clouds of hazy astral material often drift through the town, shrouding it in an eerie fog. There is no real central government to speak of, but the presence of the god's enigmatic and malevolent soul casts an inescapable shadow of dread over the town. And while many townsfolk make the best of their situation and find ways to enjoy themselves, the stark reality that everyone is walking on the bones of an enormous corpse that isn't quite dead can never be completely forgotten.
The population of Bleak Haven is a more or less random hodgepodge of races. Just about any race can show up here. Most of the population is transient, using the location simply as a convenient safe harbor between spelljamming voyages. At any given time, there are usually around 5,000 people in the town. The primary language is Planar Common (the same Common that is spoken in the city of Sigil). Gith is also prevalently used.
The god's skull is the headquarters of the Eternals, a cult that considers themselves the governing faction of Bleak Haven. Here they have their temples, barracks, workshops, and residences. They patrol the town and make sure their laws are obeyed, but for the most part they expect little of the townsfolk. Their primary edicts are that none can enter the Skull without their permission, no other gods can be worshipped in Bleak Haven, the god itself cannot be harmed or vandalized, and the cult's religious rituals cannot be interfered with. They conduct occasional sacrifices, which they believe are necessary for keeping the god pacified and bringing about his eventual reawakening. Townsfolk tend to leave the Eternals alone and at least make pretenses of obedience when patrols are around, especially since the dead god appears to support them. If any try to make an overt move against the Eternals’ HQ or leadership, the god’s shadow interferes directly to stop it.
The Eternals are a race unique to this setting, slender almost to the point of appearing emaciated, and with vague, nearly featureless faces. They wear cloaks and masks so that their true forms are rarely seen. They were once githyanki who were living on the dead god, but after accidentally awakening the lingering vestiges of his soul, they were twisted and corrupted by him. If an Eternal is killed, the offender vanishes without a trace. Eternals never speak, but when communication of some kind is necessary, they telepathically broadcast wordless emotions.
The Eternals also control the neck area of the spinal column. They use this area as docks for their own spelljammers. The Eternals rarely leave the god’s body, but when they do, they do so from their own docks and with their own ships so as to maintain privacy and independence.
The shoulder blades of the god’s body provide a wide, spacious area for luxurious estates of successful trade barons and the like.
The sternum houses the Aethervane, a complex apparatus of arcane and mechanical components that allows skilled operators to determine when certain portals in the Astral Plane are open and to intuit the state of the astral currents between the portals and Bleak Haven. This is the primary way that PCs can figure out which destinations are available to them to adventure in during a given session, and it also serves as a prime meeting spot to hear news and rumors about recent events outside Bleak Haven. Thus, the various NPCs found around the Aethervane, such as operators and spelljamming crew, function somewhat like a “job board” for PCs.
Since the operation of the Aethervane is no simple matter, the Sternum is also where those more inclined toward arcane research can be found, and it was a logical place for the Aetherium Campus. The Aetherium is a massive organization that spans multiple worlds and planes and sponsors exploration and research. The Campus in Bleak Haven is just one of their many outposts and by no means the headquarters of the organization itself. Through its representatives in the Campus, the Aetherium sends adventurers on missions to study other worlds, but they stress the importance of avoiding cross-planar contamination and of not allowing spelljamming technology to interfere with a world-locked culture’s “natural development.” The Aetherium also tends to be somewhat obsessed with order. They have a natural affinity toward Mechanus and clockwork automations. The Campus houses the primary university and library in Bleak Haven, and the librarians serve as the town's official timekeepers and historians.
Dense clusters of buildings cling to the bones of the dead god’s rib cage, with winding streets and alleyways between them. These are where most of the residences are located. Occasional bridges (of various materials and states of repair) allow pedestrians to cross from one rib to the next without traveling all the way up to the Sternum or down to the Spine.
The spinal column is the main thoroughfare for the town. As such, it also serves as a kind of bazaar, where traders hawk their wares. The bazaar is largely controlled by organized crime. Gangsters exercise control over what gets sold and where, how much can be charged for it, and where the profits go. In exchange, they provide a certain level of protection to the merchants there.
The vertebrae toward the base of the god’s body serve as the docks for the common traders’ and travelers’ spelljamming ships. Since the Eternals show no real interest in the security of others in Bleak Haven, the spelljamming crews must hire their own guards to protect their ships while in the harbor. The Spelljamming Guild of Bleak Haven maintains a collective of guild-approved guards for the purpose.
Shattered pieces of bone that once formed the god’s pelvis have been chained and lashed together here. The area provides space for warehouses and shipyards. It also has become a kind of slum for the less fortunate denizens of Bleak Haven. While designing or captaining a spelljammer comes with a certain level of prestige and respect, the common sailors, shipbuilders, and dockworkers tend to get rather short thrift.
It bears mentioning that life in the Astral Plane is quite different than on many other planes, and those same idiosyncrasies apply to life in Bleak Haven, such as it is. In particular:
Who exactly the god was is a mystery, but what is known is that the god was once an extremely powerful and evil deity. Now, however, the god is almost entirely lifeless. Only a small vestige of the god’s soul remains.
The vestige of the god's soul serves to protect the town and the surrounding area. This doesn’t seem to be an act of benevolence on the god’s part, but rather some lingering instinct for self-preservation. In general, travelers can come and go, bearing whatever cargo they wish, but especially powerful materials and entities find themselves barred from entering the god’s sphere of influence. Even other gods find themselves unable to overcome this barrier, which suggests that the dead god was once extraordinarily powerful. Also, certain magical and technological items are rendered inert if they are carried within the god’s zone of influence.
Not everyone in Bleak Haven gets along, but the denizens tend to keep their competitions and rivalries subtle and nonviolent. This is because whenever violence reaches a certain threshold in Bleak Haven, the soul of the dead god has a way of manifesting itself (typically as a red mist) and painfully ripping the offenders apart, claiming their soul for eternity (regardless of how justified or moral they may have felt their actions were). No one knows exactly what it takes to set the dead god off or how exactly he will react when that happens, so most don’t push their luck. Most people are there simply to make a trade or find a place to rest before heading off to some other destination, and they aren’t looking for trouble.
In practice, this sphere of protection allows the Gamekeepers to maintain the town as a neutral and stable hub location, preventing coups and stopping PCs from transporting unbalancing items from one adventure location to another.
Travel to and from Bleak Haven is primarily conducted via planar portals and spelljammers. However, portals (including color pools) tend to appear and vanish unpredictably, which restricts the locations a party of PCs can visit in practice.