Yliakum is an underground city. The inhabitants, a mixture of different races, also call it the "City of the Azure Sun", referring to the huge crystal that gives the city its light and supplies the land with life-giving energy. Yliakum is located thousands of meters under the surface inside a huge excavated stalactite, hanging inside a cave so huge that it could contain any kingdom of the surface. For this reason it is structured in grades - like Dante's Inferno - and each grade is smaller than the former. There are eight grades, or levels. The two highest levels are above the point where the stalactite connects to the roof of the cave.
The Bronze Doors, located along the perimeter of the first level, access the Stone Labyrinths, a complex of both natural and artificial caves as ancient as the town itself. It is sure that some of them lead to places similar to Yliakum and even to the surface, but nobody ever came back to report such a discovery. The Stone Labyrinths are one of the sources of food and resources for the city.
Inhabitants of Yliakum hunt not only the animals inside these caves for their edible meat and warm furs, but also fungi, molds, and saprophytes. These plants cannot be found elsewhere, since there are no other suitable environments for them, and their curative and helpful properties are valuable to the people. Like all places, there are also more pernicious and aggressive creatures living here as well from each of the four natural kingdoms. Hunters and gatherers must keep an eye out for these predators, who create an obstacle for those who venture in the less controlled and more dangerous tunnels of the Stone Labyrinths. As always in places of danger, great sources of wealth are just waiting in these caves for someone clever enough to find and profit from them.
Many different underground streams spring from the walls of the first and second levels, some of which were formed from time immemorial, and join together at the bottom of the stalactite, where they form a lake that submerges the two lower levels. Somehow the water gets out, since Yliakum hasn't been flooded once in recorded history. The flow of the streams varies as times goes by, and the level of the lake changes accordingly. Sometimes the lake level is so low that almost half of the seventh level is revealed, but other times the level is so high it almost reaches the edge of the sixth level. The springs here supply a constant source of drinking water for Yliakum.
The seventh and eight level, both usually submerged, host the Nolthrir, an Elven race who have been attending the seaweed for thousands of years. With the influence of time and the Crystal, the Nolthrir evolved into an amphibious species, which enabled them to remain under water for long periods of time. After centuries of crossbreeding, the seaweeds have been grown with such skill by the Nolthrir that they boast special qualities. Some of these varieties are used as food, while others are tanned and woven to make clothing. Still others have medicinal properties, but most of the seaweed is dried and used as fodder for Pterosaurs, Megaras, and cattle bred on the first level.
The Crystal that brings light to Yliakum is an enormous raw stone of purest transparency and analogous to the sapphire that hangs from the roof of the stalactite's internal cave.
Named the Azure Sun by those races that still remember the surface, it emits a radiation that is more towards infrared if compared to the light of the sun, but is suitable for photosynthesis and survival of many animals, vegetables, and mineral species. This radiation decays with squared progression with the distance. At the seventh level the radiation is just enough to penetrate the mass of the lake in order to light it, while on the first level it is so strong that it allows wonderful crops and the breeding of great cattle, which provide milk and meat.
To the great regret of the scientists, radiation from the Crystal keeps them from exploring too near. Using logic and common sense, scientists concluded that the nearer than twelve steps from the Crystal, the radiation dissociates matter, sometimes even generating random chain reactions that could be very dangerous. However, since the Crystal is such a powerful source of every kind of magic in the city, some fool will dare to get too close and risk the dangers.
The Crystal draws its light from the surface and thus Yliakum is subjected to times of "day" and "night". However, even at night, it is not completely dark. The level of the lake, which rises and falls in an extremely consistent manner, measures hours. A wide band of the metal Orichalc was put on a section of the sixth wall and was used not only because it is the only metal that doesn't deteriorate whatsoever, but also because underwater flora cannot take root in it. The names of the six periods that divide each of the four seasons are carved on this band, and information about the periods is engraved over the level reports.
The year is subdivided into four seasons only because of the cultural heritage of the people coming from the surface and the observation of the cyclic phenomena of vegetable growth. During the twenty-four periods of the year, the Crystal's azure light varies marginally, helping to reinforce the different periods.
The Pterosaurs are reptiles with organs adapted to flight, such as their membranous wings and long tails, which they use as a rudder. The Pterosaurs' dimensions vary from three to six meters, not including their tails, and their wingspan is directly proportionate to their bodies. From the moment they are born, Pterosaurs begin training to carry a person sitting in a saddle buckled between the animal's shoulder blades. Pterosaurs must be at least three years old and fully trained before they can actually carry a person, which makes them precious, coveted, and very expensive to keep. Only extremely wealthy people can afford these lizards, but no matter how wealthy a family is they may only legally own a single Pterosaur. The law forbids owning more than one of these animals in order to avoid dangerously crowding the limited air space.
The second flying animal is the Megaras, which is similar to a giant bat. Scientists believe the Crystal has genetically mutated the Megaras, since they reproduce only in Yliakum. These bat-like creatures are not as docile as the Pterosaurs, but they are stronger and more efficient, making them perfect to carry heavy but not too delicate loads, such as food and building materials. As with the Pterosaurs, each mercantile society is allowed to own only one Megaras.
Ducts that have been dug out in the rock are used to dispose of human waste. Larger rubbish and bodies are simply thrown into almost vertical and apparently endless wells. Nobody seems to care about where all of this junk finally ends up, since the stalactite theory is only devised by some Xacha scientists and has not been proven yet. Dead bodies are eliminated the same way. Though discarding dead in such a callous fashion would seem rather shocking, neither of the two main faiths at Yliakum requires particular care nor reverence to dead bodies. To the people here, a body is simply a non-functional apparatus or an empty shell with no soul. However, nothing is ever thrown into the lake. The law forbids this disposal method not only out of courtesy to the Nolthrirs, but also to protect the seaweed population. Polluting the lake is one of the few crimes punished with death.