It's very interesting to be able to see and use the historic telescope. When it was built in 1885, the 26-inch astrometric refractor was the second largest telescope in the world. It's fascinating to see all the original parts and to realize that nothing has been updated (with the exception of a few electronic upgrades) and yet they discovered the distances to thousands of stars. The dome is still moved by ropes and pulleys and the doors open manually with the pulleys. You have to get a free ticket to attend one of the Friday public night programs and the tickets can go pretty fast when they are released one month in advance (on the first business day of the month). There is a short educational program before you are able to use the telescope. For our program, we had a post-doc who was not a good presenter at all, and so that was kind of painful to sit through. The staffer explaining the history and function of the telescope was outstanding - extremely knowledgeable, a good communicator, and personable. The only bad thing is that due to the historic nature of the telescope and the fact that it has one-of-a-kind parts, they cannot open the dome when there is rain. It's perfectly understandable and they say you can still come to hear the lectures, but I would recommend not going if the weather is bad and trying to get tickets for a later date.