I think I know the reason why. I had only a moment to take the shot so I hand held the camera and focused on the pyramid. Double click on the image to see my lumpy building.
1/1000 sec at f8.0
focal length 36.28
Actually it is ‘lumpy.’ You can read about the concrete blocks making up the tower on the following website. http://www.emporis.com/building/transamericapyramid-sanfrancisco-ca-usa