The Russian word for Moscow is Москва. It's а perfectly regular second declension noun:

Now if you are a foreigner and you want to prove how stupid an American is, simply ask “What is the name of the main river that runs through Moscow?” Sadly, most Americans will probably look at you like a deer caught in headlights and say “Idunno.” (I'm sitting in my favorite coffee shop as I type this entry, and I just tried that question on the barista. He was stumped.) It's funny. Sometimes American education produces profoundly well-rounded and insightful people, but when it comes to geography almost all Americans come up short.

So for my American readers I should point out that the main river that runs through Moscow is called… are you ready for this?… the Moscow River! (Москва-река in Russian, always hyphenated.)