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Yerkes Observatory

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Address: 373 W. Geneva Street, Williams Bay, WI 53191
Phone Number: 12622455555

Yerkes Observatory is owned and operated by the University Chicago,...

Yerkes Observatory is owned and operated by the University Chicago, Department of Astronomy and Astrophysics, and located in Williams Bay, Wisconsin.

Built between 1895 and 1897 in the classic Romanesque style, Yerkes is home to the largest refracting (lens-type) telescope in the world and two other research-grade reflecting (mirror-type) telescopes. The building is beautifully preserved and ornamented with Roman brick and terra cotta, has three telescope domes (the largest is 90 feet in diameter and 10 stories in height), and is situated on 77 acres in a park-like setting.

Tours of the building and the refractor are available Monday through Friday ( the cost is $25 for a brief overview tour, or $100 for a longer, extensive tour) all year. Call the Observatory in advance or stop by between 9:30 am until 4:00 pm.

Saturday tours are held for the public at 10:15 am, 11:15 am, and 12:15 pm. Reservations are not required. While free to visitors, the suggested donation on Saturdays is $5 per person.

The grounds are open every day, during daylight hours, for self-guided walking tours, free of charge. Photography is permitted.

The staff also hosts public observing sessions with the 24-inch reflecting telescope many evenings throughout the year. Reservations are required and there is a charge for participation. Call the Observatory during regular weekday hours or visit the Yerkes website for more information.

The Observatory contains a lovely museum, many interesting displays concerning its construction, history, architecture and the science of astronomy, and a gift shop with many unique items.

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TripAdvisor Reviewer Highlights

Read all 111 reviews
Visitor rating
  • 80
  • 25
    Very good
  • 4
  • 1
  • 0
40" Observing Session

This is a unique experience and truly special - but to be clear it is not the viewing through the telescope that is the draw. The view through the telescope is approximate to... read more

4 of 5 starsReviewed 2 days ago
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111 Reviews from our TripAdvisor Community

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Showing 110: English reviews
Level Contributor
35 reviews
15 attraction reviews
common_n_attraction_reviews_1bd8 48 helpful votes
4 of 5 stars Reviewed 2 days ago NEW

This is a unique experience and truly special - but to be clear it is not the viewing through the telescope that is the draw. The view through the telescope is approximate to many other more modern telescopes that are readily accessible through other universities, observatories and astronomy festivals (though to be fair our viewing was significantly hindered by the... More 

Thank memcc
New Lenox, Illinois
Level Contributor
108 reviews
21 attraction reviews
common_n_attraction_reviews_1bd8 42 helpful votes
5 of 5 stars Reviewed 1 week ago NEW via mobile

Cool, wet, and windy? We went here. Weekends there are three tour times (last at noon). The tour included 2 parts...the observatory history, operations, astronomy, etc...and the building/grounds. Took about 45 minutes. Small (about 15 people) private classes at night (July) for lunar observation. Check for more details. Really enjoyed our time there. Finished with lunch in William Bay at... More 

Thank Rmangun
Wood Dale, Illinois
Level Contributor
36 reviews
18 attraction reviews
common_n_attraction_reviews_1bd8 15 helpful votes
5 of 5 stars Reviewed June 13, 2016 via mobile

Look at website for tour details but this time of year, tours are Monday thru Friday at 10, 11 and 2. There are also Saturday tours. They are closed on Sunday. Tours are free (they ask for a donation). But if you want to actually peer through the telescope (rather than just seeing it from a distance), those tours cost... More 

Thank Familyof4fromChicago
Level Contributor
421 reviews
303 attraction reviews
common_n_attraction_reviews_1bd8 116 helpful votes
5 of 5 stars Reviewed June 5, 2016

Open to the public from 9:45 a.m. to 1:30 p.m. every Saturday throughout the year. Saturday tours begin at 10:00 a.m., 11:00 a.m., and 12:00 p.m. Most tours last 45 to 50 minutes. They do not accept reservations. The interior of the 90-foot dome is not temperature controlled, so dress appropriately. Don't forget to browse their unique gift shop. There... More 

Thank Anna G
Dan K, Manager at Yerkes Observatory, responded to this review

Thank you for your review. One clarification though. Yerkes is open for tours six days a week, Monday through Saturday. The Observatory is closed on Sundays. Weekday tour times change with the season and are posted on the Observatory website. In June and August 2016 tours will be conducted at 10 am, 11 am and 2 pm. In July 2016... More 

Level Contributor
20 reviews
7 attraction reviews
common_n_attraction_reviews_1bd8 16 helpful votes
4 of 5 stars Reviewed June 4, 2016

Observe with a Yerkes Observatory Telescope - 40" Diameter Refractor Telescope Tour - This information is located under the "Visit" link and then click the yellow link for the info. on the 24" and 40" tours. They just started these tours in February 2016. If you can afford the $100 pp for the 40", do it. You see more detail.... More 

Thank Chgotourist
Chicago, Illinois
Level Contributor
86 reviews
17 attraction reviews
common_n_attraction_reviews_1bd8 22 helpful votes
4 of 5 stars Reviewed May 16, 2016

A short drive from town, this building history and architecture were fascinating, aside from the impressive tour of the telescope. The tour was very informative and our guide was very enthusiastic about sharing his knowledge. We'd love to go back for a night time view , tho it is totally dependent on weather conditions.

Thank JRB_Travels
Fort Thomas, Kentucky
Level Contributor
4 reviews
common_n_attraction_reviews_1bd8 1 helpful vote
5 of 5 stars Reviewed May 4, 2016

The guide was extremely informative and flexible with my young boys and their short attention spans. The size of the telescope is amazing.

Thank Susan W
Madison, Wisconsin
Level Contributor
47 reviews
11 attraction reviews
common_n_attraction_reviews_1bd8 7 helpful votes
5 of 5 stars Reviewed April 11, 2016

This was an amazing experience to visit and learn a little bit about astronomy, history. Very interesting I think to any age. Well worth the visit.

Thank zeusy33
Level Contributor
6 reviews
4 attraction reviews
common_n_attraction_reviews_1bd8 1 helpful vote
4 of 5 stars Reviewed April 10, 2016 via mobile

Went for the tour purchased through Groupon, so it was $18 for me plus 3. I'd definitely recommend seeing if a Groupon discount is available. Enjoyed the historical narrative and the architecture. The 9 year old was very interested, but I think young children would be bored to tears as it's not a hands on type of place. Would like... More 

Thank Chan T
Dan K, Director of Sales at Yerkes Observatory, responded to this review

Thank you for visiting Yerkes and providing a review of your experience at TripAdvisor. We are glad you enjoyed the tour with your family. As mentioned on our website and printed materials, our tours are recommended for ages 6 and up. You are correct in writing that small children probably won't find the Observatory interesting since Yerkes is a historic,... More 

Level Contributor
31 reviews
3 attraction reviews
common_n_attraction_reviews_1bd8 8 helpful votes
5 of 5 stars Reviewed April 9, 2016

Excellent, informative tour of an historic institution. Our guide was terrific. Knowledgeable with a sense of humor. It is home to the largest refracting telescope in the world and the building is great.

Thank jaamo

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