Basic Information:
Acheron is made up of nine key levels of called circles, each like a plane in and of itself, and the Barrenlands which forms an outland surface over Acheron. Planar doors lead from one circle of Acheron to the next making it seem far smaller than it actually is, for the distance to cross between each circle is so great, that any mortal would die of old age, and any immortal would have wasted hundreds of years before completing the journey if not for the gateways which let travelers cross from one level to the next.

Acheron is like a planet in its structure but not its shape, and is not a planet. Acheron is a vast living breathing entity whose contours make up the surface of a galaxy sized world, while interior cavities and air pockets make up the cavern underworld which shelters the main population of its denizens and purgators. Acheron if it could all be seen at once might appear as a vast deepsea fish hanging in the great rift of space within the throat of the universal hourglass. Acheron lies at the very center of the universe, between the two poles of the middle kingdom and the upper kingdom, with the great spike of the void thrusting through its spout and exiting through the bowls of its belly, the abyss. Acheron expands and contracts around its complex network of caverns and the abyss at its greatest depths does so, as if breathing, and the stone-like walls around its many chambers and pathways breathes as well, without fracturing. This occurs over ages in time typically so is not noticed by those residing in Acheron. It is from the great valley of the barren lands that Acheron's 1st Gate is accessed, from the Atrium between two pillars out of five which form a pentagon with huge arched lintels of bone. Though the living can be taken into Acheron, it seldom happens unless a being learns too much, has given themself to one of Acheron's lords, has made it past the gate guardian Abraxas, or has crossed one of Acheron's lords. Even fewer outlanders ever leave Acheron unchanged. Acheron is a dangerous underworld to enter as a trespasser on the best of days.

Braemen decribing Acheron: "Vast... it is Acheron, like so many worlds beneath a roof of stone tied together by a network of caverns and tunnels, while up above a wilderness that is mostly wasteland as endless stretches out beneath three stars in a dusky firmament which darkens to a twilight sky at night. Named for what it is, the Barrenlands appear mostly flat, for it IS a world with curves so tremendous and gradual that one cannot tell it curves at all. Soft sand or dirt covers the bedrock in some areas, while crystals stud the ground in others so sharp they bruise your feet through armor. The bedrock breaks the ground in other areas for miles... smooth and hard, rough and jagged, or broken with cracks. Two ancient mountain ranges stand as walls on either side of the flats on the northern hemishphere east and west, a volcanic cresent of mountains far to the south. With the flats in between these mountains; two massive towers of curved stone stand like immense horns marking the beginning of each range east and west. Beneath these horns are two gigantic spheres of stone with striated, diaphanous and scintillating interiors of cloudy white, pink, jade green, amber, and sky blue, which some call the eyes of Acheron. The Barrenlands are desert, but with a climate remarkably unremarkable, neither hot nor cold, until the wind tears over the sand flats to sting you with the dust and haze it raises up, or a cyclone of dust and crystal glass chases after you hungry to cut you to pieces or to rip you apart. Then there are the shallow seas in the south central crater of the southern hemisphere which extend from horizon to horizon no deeper than your waist, else you find the SINGLE place that sea deepens to swallow you up into a pit of slippery clay, and oh the strangeness of the storms which can erupt over this knee deep sea. A riot of crashing waves can rise up in a torent to pound against your face and body with such savagery as can cause a man to drown in the shallow brine. Nothing dwells in the Barrenlands that is not spawned in the shallow salt sea called the Spawning Sea, else someone chooses to dwell there because so few ever would. There are two great forests in the Barrenlands, with enormous and dense trees like non other ever seen, twisted, strange and strewn with moss and vines. The Barrenlands is the skin of Acheron, whose caverns, chambers, cities, palaces, lairs and corridors surround the Eternal Wastes, the Lost Caverns, and the Halls, caverns and chambers of the condemned, the Purgators."

Acheron is heavily warded by powerful fields and spells, many of which were raised by its mages out of the altars and shrines of this vast underworld. One of Acheron's powers is 'Legendary Enigma' which insures that Hell remains unknown to outsiders, as a myth or legend that no one has proven the existence of. This power protects the few and hard to come by maps of Acheron's levels and prevents divination and scrying powers from the outside.

The Barren Lands:
The surface above Acheron is called the barren lands, and is made up of a valleys, deserts, desolate canyons, rugged mountains, primeval forests, and volcanoes. In the great valley there is also a shallow, flat salt sea, and one river. The single river comes out of the mountains to cut through the deserts and canyons. Within the great valley of the barren lands is Acheron's Atrium, a receiving yard which is marked by a hexagonal ring of pylons bridged by stone arches. The entrance to the Antechamber of Acheron's 1st Gate is little more than an open space between two of the towering pylons, bridged by an elaborately carved lintel of stone. These pylons form six thresholds which look exactly alike. If someone passes beneath the right lintel, they enter Acheron's black, domed antechamber, where they are met by the angel of despair. If they pass beneath any other lintel, they find themselves standing on hard packed sand in the barren lands, out of sight of the Atrium.

The Nine Gates of Acheron
1st enters Acheron from Morashtar
2nd unknown
3rd from the nether march which accesses the kingdoms of the Lower Kingdom.
4th from Antares Three (a modern, fast paced, often dangerous futuristic world with intelligent sentient beings)
5th-8th unknown
9th from earth intersecting its parallels

Acheron's Antechamber:
whatever gate one enters into Acheron, they enter first into Acheron's antechamber and then its gauntlet. All who trespass in Acheron are met in the Antechamber by the Angel of Despair, Abraxas, whose penance it is to serve as the chamber's guardian for the remainder of his life. In order to enter Acheron's Gauntlet beyond the Antechamber, one either has to get past Abraxas, defeat him in battle, or achieve his permission to pass. The stone door to Acheron's First Level is sealed by an enchanted key, and Abraxas has the key. If Abraxas is amiss as a result of injury or death, the gate is left ungarded and the key can be found somewhere in the antechamber. This is not to say that one of Acheron's own will not meet a trespasser in the antechamber. Each level of Acheron is called a circle.