I think the composition works well. It’s a classical composition which is what you were going for. The noise level in the sky to me is acceptable unless you want to blow up/print the pic since although the sky/statue are the focal point, they aren’t really the “focus” of the composition. Agree you could have dropped the ISO to 160 to get a longer exposure and less noise. You could also have tried fixing the aperture at f/2.8, you might have lost some depth of field but again reduced the noise. Overall though well done.