Once when I was in London I heard an airplane flying low overhead. I looked up and saw the very distinctive silhouette of the Concorde. It must have been one of it’s last flights; soon after this the Concorde was grounded.
As a guide to get the perspective of the buildings right, I studied drawings from the book “Perspective Made Easy” by Ernest R. Norling. He points out that the tops of all the buildings are made with square corners, but that it’s not a hard and fast rule.