Right, right, but how big is the city? Is it a city the size of Oklahoma or the size of Sacramento? Assuming you even know what those cities are, I'm not sure yet how similar or different all our words are geographically.

There's a number of factors that go into what size an animal can be, but when we're talking about big creatures like this the biggest influence is gravity. Basically if you are big, you weigh more, and the greater the pressures are on your body. And there's only so much weight that your bones can support! And you could just have bigger, stronger bones, but they're heavy too, so eventually you'd just collapse under your own weight.

Of course this isn't as big an issue for creatures that live in the ocean, as the buoyancy effects of water means that you weigh less. So sea animals can get a lot bigger - but those pressures are still there, and this turtle has got to be way over the limit! Unless somehow it's got something that gives it really, really, really good buoyancy to offset the issues...