Be sure to send them an email first, so that you can arrive at the proper time for them to give you a tour. It is very, very worth it. One of the best museum experiences so far.
Thanks to both of you for the info. I'm longtime Seattle and I had no idea. I'm still disappointed that the living computer museum was closed. Jody Allen is a decent person so was surprised she let that tiny line item expire from the spreadsheet, I digress.
+1 to this! If you have any interest in telephones, telephone switching, or phreaking, this place is incredible. And the people who run it are awesome.
https://www.telcomhistory.org/ConnectionsSeattle.html
The volunteers there maintain a bunch of functioning cool vintage equipment you can see in action and even use.