When you look at it straight on, the building resembles the bow of a ship sinking into the street.
The optical effect is the result of a tricky perspective, the kind I have to think through carefully before putting pen to paper. The key is to realize that the vantage point for the sloping street is high above the horizon line. Then, to understand the positioning of the garage structure, I imagine it as if it was on flat ground. That helps me notice that the windows aren't parallel to the sloping street, but to the base of the building hidden by the inclination of the street.
The experience of sketching that garage by the Smith Tower years ago still comes handy any time I sketch similar perspectives. Most recently, I encountered this other "sinking ship" in the Denny Triangle during a sketch outing with the Seattle Urban Skechers:
For more tips and examples of drawing architecture, check out my upcoming book, The Urban Sketching Handbook, Architecture and Cityscapes. It's coming out this fall!