There are twelve murals and they were completed in 1980 by Nancy Lynch, who was married to James Novak, the manager of the cafeteria at the time. There are twelve panels, one for each of the exterior sides of the dodecagon that makes up the walls of the ballroom.
The mural starts with the old Indian school that occupied what is now Drexel Hall. (Here is a history of the Indian School written by Fr Dominic Gerlach.)
link to the video on Youtube.)