My travels brought me cross-country this evening, and a perfect chance to try out a city shot with the 18-270. I chose to use half of the frame, in order to make use of the curve above the doorway, and the contrasting colours. The lens resolves well, with no unsightly degradation of the circular elements of the building. There was a spotlight in the lower half of the photo which caused a flare spot on the section that you see here, but it was easily corrected due to its uniform colour and shape.
Nikon D300; Tamron 18-270mm @ 18mm; 200 ISO; f/13; 5 seconds. VC off.