it was all in one go, although I think I made the paper a little to wet. I premixed all my colors first. Start with the raw sienna and then some shadows and then the blue. Cerulean granulates very easily so I should have mixed in some cobalt blue - I usually do, this time I didn't. I'm happy with the cityscape though - that was fun to do with a couple of flat brushes. I live just below the two two chimneys in the green area ;-))