The buildings are CSG. The flag was made in Wings3d. I simulated the decorative ironwork on the balconies using a turbulated crackle, flipped and repeated accordingly. The bannister railings on the flag tower were made with SpilinEditor. The roof tiles are CSG, rotated and placed from within a loop.
The main research-and-development innovation in the making of this image was the cumulus clouds. They are built up using trace and eval_pigment in order to give them a suitable bumpy appearance. I also used crackle form as a texture on the clouds to make them look bumpier. I think the technique makes pretty good cumulus clouds, in terms of overall shape and color.