Newbie post here! I've been a member for all of one day but have been visiting abandoned sites for about 5 years. I will eventually share some of my old haunts but decided to take advantage of the nice weather today and drive to a local abandoned observatory. Still learning how to post photos here so bear with me.
The observatory operated from 1933 to 2005. In its heyday, the observatory discovered a number of planets outside the Solar System. It also housed an 84-foot radio antenna and 61-inch telescope once used in Project BETA, to search for extraterrestrial intelligence. Fun fact... this was partly funded by Steven Spielberg. The site still does some observations, I believe, but are recorded remotely. In the pictures below, you can see where a few old telescopes were once mounted. I also loved the sun symbol marking the optical telescope building. Imagine climbing up there in winter to grease the wheels so the darn thing opens.
I didn't take a lot of pictures as it was heavily shuttered. Still a cool place to check out!