… The nameless city, for such it was even when it was inhabited, stood for well over a thousand years in the depths of the Fell Forest. It was not called the Fell Forest or any other name then. The wizards and sorcerers of the city introduced the gnoll tribes to the forest, hoping that they would discourage uninvited guests. The ploy worked beyond their wildest dreams, as few people visited in the ages since.
A millenium later, The city's basalt towers still stood, perfect and undamaged through centuries of neglect, a silent testament to the skill of those wizards who raised them from the earth. The city's builders formed a cabal of mages who turned their back on the world to pursue their research in secret, and it was a great experiment. The emblems of Uncaring Boccob and Wee Jas, deities of magic, were etched into the sides of each tower, in hope that those gods might bless the endeavor and watch over the city. In fact, no such thing happened.
No one knew any of this in the walled frontier cities of Atupal and Klionne, places remarkably lacking in curiosity regarding any history, including their own. Centuries after the abandonment of the towers, the residents of the closest towns had no idea that they shared a common origin; indeed, they had no idea that the towers even existed. The wizards' city was erected in a deep valley within the forest, so that even the tallest of its towers were not visible to the outside world. Thus was their privacy ensured. The location was so secret that mention of it survived only in scattered, ancient tombs and nearly forgotten myths.
The story of the city's fall was inglorious. No plague, no war or disaster claimed its inhabitants but merely time and waning commitment. The city's original inhabitants were content to lock themselves away with their books and spells, but the same was not true of their children and grandchildren. Despite fears that the city's secrets would be lost, eventually malcontents were allowed to leave the city if they promised never to speak of its existence. Some of these emigrants established themselves as the heroes and rulers of an age. All kept their promises and never spoke of their home.
Still, the magicians' efforts to protect the nameless city proved fruitless. The city was never betrayed, but its vitality and life slowly ebbed away as later generations were drawn into the wider world. The experiment failed. As the last inhabitants grew old and died, the city was left to the ravages of the Fell Forest. Nature moved in, but even it could not erase the enchanted architecture. The towers remained. More importantly, locked away in the bowels of the city were potent artifacts of the wizards, items whose existence couldn't be hidden forever. Eventually, adventurers, antiquarians, and treasure-seekers came to the Fell Forest in search of power and knowledge.
Some stumbled upon the last remaining references to the nameless city and went looking for it. Others set out blindly across the Berron Bridge into the Fell Forest with little idea of what awaited them. Most would be killed by the orcs, gnolls, or other local menaces for their weapons and armor.
All of these seekers passed through Atupal or Klionne before jumping off into the forest, and they were unfailingly surprised by the locals' lack of interest in what might lie beyond the screen of trees. Some adventurers elected to pass through in secret to avoid drawing derision from merchants and farmers.
Such was the case with a group of four heavily armed humans who passed through Klionne. They made no mention of seeking the nameless city. Once inside the Fell Forest, all their skill was needed to evade wolf packs and fight off orcs. They found it nearly impossible to navigate through the dense timber. Tired and desperate, they eventually stumbled upon the legendary lost city, through luck as much as planning. The gnolls and orcs would not pursue them into its silent streets, and the adventurers foolishly assumed they were safe within its boundaries.
But the arcane architects were not fools, and their treasures were not for the unwary. The world might never know what triggered the eruption, but soon after the intruders' arrival, a torrent of cold poured from the city's central courtyard. The initial blast of frost was too much for the weakened humans, and it was only the first wave of an arctic deluge that would flow across the hills and valleys, destroy the Fell Forest, and ultimately threaten to bury the whole region beneath a glittering glaze of dazzling, deathly white.