The buildings volume, and the one that fixes the most common wreck. Perspective without the textbook: finding eye level, one and two vanishing points, how to draw a street that runs uphill, how to fake a crowd of windows without counting every one. Then texture — brick, glass, corrugated iron, wet asphalt — and how to decide what to leave out, which is most of the skill. Short chapters, his sketches next to sketches from other Urban Sketchers, and a lot of before-and-after showing where a drawing went wrong and why.
The Urban Sketching Handbook: Architecture and Cityscapes