If you are unfamiliar with Hillenbrand Hall, this might help you visualize this very important part of the story:
The parking garage is located in the very bottom left (you can see the lines on the roof). The East tower is on the right and has a darker roof. The front entrance is in the center at the top (green roof). Photo courtesy of Hinshaw Roofing.
I'm not sure if this sort of media would make the final cut of any serious edit of my novel, but here it is anyway - I make such an effort to physically describe the setting that I wanted to make sure everybody was on the same page.