Yeenoghu's Moving City was a massive, mobile unit, controlled by the Gnoll God Yeenoghu, held in the air by an army of Gnolls. The city, a cluster of buildings sitting atop a series of platforms held by the army, moved at an exceedingly slow place, and would pilage and destroy any civilized structures they came across, including other cities.
Aludra Wyrmsbane and Thom Vidalis, along with the help of Lord Titus Harper and Zird the Arcane traveled to the city to rescue their adopted son, Bucky, from the clutches of the god Yeenoghu. Upon their arrival (at which time the city was marching toward Fallow Field), the party found that Yeennoghu had been slain by Fennekin, and the creature's skin was given to Bucky, corrupting him, his friend Ros, and traveling companion/pet, Daisy. After Aludra removed skin, Zird realized that Fennekin, having been able to slay the Gnoll God, was too powerful for them to stop as things currently were. He sacrificed himself to bring about the Fifth Edition of Magic, so that the others could defeat Fennekin, and end the Demon Apocalypse.
After the party left, Yeenoghu's Fortress, in the center of the City, was destroyed, and collapsed on top of the gnolls carrying it below. It is currently unknown if the rest of the city continued on, or if the entire thing collapsed.