On June 2 my brothers and I visited the Yerkes Observatory, which is owned and operated by the University of Chicago. It’s located in Williams Bay, Wisconsin on Geneva Lake not far from Chicago.
Yerkes was built in 1897 and originally housed the telescope with the world’s widest aperture, a 40-inch refractor. It’s still there. It had a long history of significant astronomical discoveries by prominent astronomers.
Hour-long $10 tours are conducted every day but Sunday. You learn about the unique architecture of the building, then sit near the large telescope for a lecture about it. During scheduled evenings you can observe through the large telescope for $100.
The tour and accompanying lectures are marvelous. The reason for the fees is that the U of C will divest itself from association with the observatory on 2018 OCT 01. Local residents who perform docent duties including lecturing are in the process of raising funds so that they can keep the observatory running and continue providing tours.
If you are living in or visiting Northern Illinois or Southern Wisconsin, I highly recommend touring Yerkes. Here’s a link to its website: http://astro.uchicago.edu/yerkes