The Yerkes Observatory at Williams Bay featured in this film...

While on vacation a few years ago in Williams Bay, Wisconsin, I was in the middle of a six-mile cross-country run on a rural road when I happened upon the 77-acre Yerkes Observatory facility which overwatches Williams Bay. I thought nothing of it until I happened to see it again while watching "Chain Reaction" on video months later.

Yes, that entire scene where Keanu Reeves and Rachel Weisz are dodging the Wisconsin State Police et al., was filmed at this venerated facility in southeastern Wisconsin, just outside of Lake Geneva (one hour from Chicago).

Yerkes Observatory, built in 1897 by transportation tycoon Charles T. Yerkes for the Univeristy of Chicago, is currently owned and operated by the Department of Astronomy and Astrophysics at the University of Chicago, which uses it to conduct its field research activities. A breathtaking view overlooking the bay can be had atop the observatory. Notably, Yerkes Observatory is home to the world's largest refractory telescope.