This is a single colony city, Keuschburg, which I developed for my campaign background, Spheres.  It is located on New Durban, a moon in the Luyten system.  It's actually a rather unremarkable colony city: entirely underground, fairly well-planned (but far from perfect), with a moderate starport.  This image is pretty small -- a lot of the details have become rather blurry -- but you still get the general idea.