Living Computer Museums are fascinating.

Anyone who's in Seattle for any length of time owes it to themselves to check out the Living Computer Museum: http://www.livingcomputers.org/Discover/At-The-Museum/Vintag...

In addition to the working Alto, MITS Altair, etc. they have a dedicated cold room for working vintage mainframes. You can even request an account on one of 'em so you can remotely telnet in. You're also openly invited to interact with just about any of the microcomputers they have up and running that day.

That's just a small part of their collection. Neat stuff.

Also quite good is the Centre For Computing History in Cambridge.

http://www.computinghistory.org.uk/

Yeah, the amount of direct exposure you have to the collection is pretty stunning. If I remember correctly only the Alto was behind a display. Everything else you could touch/interact with.

Highly recommended.

Yes, this was also accomplished on a PDP-10 at Caltech around 1972.