Score by Michel Legrand and Boston locations
To me the best things about this movie are the Boston locations (a lot of these look very different now) and the great score by Legrand. "The Windmills of Your Mind" is a great song (music by Legrand, lyrics by Bergman). Noel Harrison wasn't the greatest singer, but he puts it across ok.
Shot of McQueen & Dunaway on the set for the steam room scene:
http://4.bp.blogspot.com/-47S0qPqjyVg/T02MZFA1UvI/AAAAAAAAHYQ/1vZwNPxt FoE/s1600/Faye+Dunaway+&+Steve+McQueen+sharing+a+sauna+as+movie+di r.+Norman+Jewison+(R)+focuses+a+lense+while+directing+them+in+a+rehear sal+for+the+movie+Thomas+Crown++Company.jpg