The Den is located in the middle third of Fenghast, close to the Northern wall. The Den was originally only a particularly large arena pit, but now the name refers as much to the underground complex that grew later as it does to the pit itself.
The Den has always been the largest arena in Fenghast, and because of it's policy of having a show going twenty hours out of every twenty four, there are always droves of spectators coming and going. To cater to these many visitors, an entrepeneur whose name as been lost to history dug a trench at the edge of the stands, under the Den's preexisting oilskin. He set up a bar and gift shop in this trench, and was immensely successful. Others followed suit, and soon there were taverns and other businesses all around the edge of the Den. Still, there were more aspiring business owners who wanted to open shop there, so a tunnel was built under the ring of establishments that were already there.
As more people came, the tunnel went deeper and deeper, and it became a downward spiral that goes all the way underneath the arena. The original Den is now a cone suspened in the center of a man made crater. There is a continuous ramp from ground level to the bottom floor, and it is possible for a round object dropped at the top of the ramp to roll all the way down. The many stalls and enclosures on the outer wall of this structure stand on individual terraces.