Actually unfortunately it wasn't. I wanted to say this made sense, but then I looked up some lore on Wowwiki:
"The climate is very similar to Burning Steppes, as it was the same catastrophe that blackened both: the summoning of Ragnaros. Searing Gorge is a part of Khaz Modan, and was a mountains region, part of the Redridge Mountains, but was shattered by the summoning. "

The last sentence is the most important. This whole region was part of a mountain range until Ragnaros decimated it.
I imagine it was something similar to what happed to the island of Krakatoa in 1883.
http://en.wikipedia.org/wiki/Krakatoa

I had thought something similar, about each Titan city being a "holding cell" for an Old God. Back when we first found out that Yoggy was being trapped in there, and was starting to break free, I thought back to the broken door and Uldum.

My thoughts were around these lines. If Yoggy could spread his tentacles around a massive portion of the continent, couldn't C'thun do the same? Especially if he had broken free much earlier, and had time to both enslave and manipulate a race (the silithid) and create his own personal set of followers.

So, once he had broken free, he spread his tentacles, enslaved and manipulated the silithid to become the Aqir, and then over time, tunneled his main core (or whatever that eye is) into Silithus, and what would become Ahn'Quiraj. Then, with an Old God tunnel straight into a Titan construct, he directed his new servants to capture and subdue some of his former captors, who, deliciously enough, were now captives of his own. (Of course he also probably drove them mad along the way, but something made of rock isn't going to be phased as much by telling them their heart will explode.)

Then I thought of Uldaman, but of course, it's not really a Titan city much. It seems like more of a storage facility, or even a repair and "powering" center that the Earthen used to use. So, while close, we don't know of any other Titan cities as of yet.

I still think that Ulduar and Uldum were used as holding cells though. Especially with the line about the Aquir adopting titan building styles. It's as if C'thun wanted to feel comfortable with his surroundings (after all, he'd likely gotten used to his prison after thousands of years), while at the same time delighting in the irony of circumstances. He's back in his "prison" sure, but now his captives are now his prisoners, while he dances them on strings of madness.

I thought C'Thun had essentially 'faked' his own death when the Old Gods and Titans were fighting. Didn't the story say that the Titans killed one Old God (Master's Glaive), thought they'd killed another (C'Thun), and imprisoned the rest?