Nemexus was built by the disembodied thinker Ingu'lumin. In the Dawn War, this marvel of engineering served as his abode and research center. When he died on 402 LE, it triggered the release of those that would come to patrol the ancient edifice and the land around. Thousands of years later, air elementals still carry out their security directives. They guard it from any that seek to get inside. When one of Nemexus's Eternal Wardens perishes, another is released from the structure's thousands of secret vaults, taking its place or carrying out the last order it was given.
Nemexus contains a library of ancient lore. These are not your normal books or rune-carved stones. Ingu'lumin's "writings", what would become called psychic imprints, are laid out with psychic energy. In effect, you have to be a mentalist to read them. These pieces of lore are scattered across a mammoth edifice covering six square miles. Some imprints are only reachable by flight, their locations among rotating rings of elemental earth motes. These psychic imprints are not orderly like a book, instead the next in the series lies somewhere else. Perhaps the worst of all is that they are always shifting places. Learning anything at Nemexus is truly a time-consuming endeavor. It is also a dangerous one. The hazards of the area are not limited to the air elementals. There are magical constructs left from the time when the place was controlled by the Lith-Crillion. The Lith-Crillion came into ownership of this place in the Maziggandîm Conflict (348 LE - 355 LE). Like the previous owners, the Tarband-Khâl, the Lith-Crillion sought Ingu'lumin's library.
The Lith-Crillion, considered by many to be one of the most advanced races, learned much more than the previous owners. They found secret chambers that could only be opened by those with a deep understanding of arcane energy. They found the mix of arcane energy and psychic energy, used in the psychic imprints, a strange combination. This led to the theory that not only was Ingu'lumin a master of the arcane, but also a highly skilled mentalist. In addition to finding ancient primordial relics, they acquired a much deeper understanding of the Web of Magic. The Libram of Aggda has an entire chapter on Web Weaver beginnings at Nemexus.