Yerkes Observatory

373 W. Geneva Street
Williams Bay , WI 53191
phone: (262) 245-5555
>> map and directions

Yerkes is the home of world's largest refractor telescope. Completed in 1897, it is owned and operated by the University of Chicago's Department of Astronomy and Astrophyics.

Yerkes Observatory offers free one-hour public tours every Saturday throughout the year beginning at 10:15 a.m., 11:15 a.m., and 12:15 pm. Donations are suggested and appreciated. Reservations are not needed. Weekday tours, at a cost that is determined by the size of the group, can be arranged by calling the Observatory.

Yerkes sponsors public observing many evenings of each month throughout the year using its 24-inch diameter reflector telescope, weather permitting. Reservations are required and may be made only by email at The charge is $32.00 per person. Visit the Observatory's website for an up-to-date list of dates and times.

Call 262-245-5555, extension 880 for more information about our tour programs.