I love the steampunk feel of this. It reminds me of a short story I read once in the book "Extraordinary Engines". It was a story about a gang of children, sort of like Fagan's kids from Oliver Twist, that accidentally saves their underground city full of giant rusty pipes from a monster of their own making. Really an interesting story. And I love how your work here reminds me of that. I also the love the feeling of massiveness you get by comparing the architecture to the two tiny figures in the lower right. Nice job!