There is a really interesting thread about a (D&D) city built around a tarrasque.
For those that don't know, in D&D the tarrasque is an immortal killing machine related to the dragons. It's immune to magic and all sorts of things that make it so it just can't be killed. It's a DM's way of ridding the world of unneeded PCs really.
But this concept is so cool that I feel the need to adopt it. It would make sense to me, since I have never used the tarrasque in any of my games even when it first appeared in the MM2 for 1st Edition. Though I have used the Piasa bird, a similar creature from my neck of the woods.
The idea behind this city is they have captured and immobilized it. Now they are feeding off of it's meat and blood which regenerates all the time. There is a corrupting power to this, plus the moral corruption of keeping a live beast chained up while you continously hack bits of it off. Something we saw in the Torchwood episode Meat.
Plus it is the type fantastical, out of this world crazieness that I love to have in my games. Cities built on the corpses of dead gods; Elven nations of thousands living in the trees and a city built around a Tarrasque.