I just came back from the The National Museum of Computing (TNMOC) in the UK at Bletchley Park. It was fantastic. They have a wide variety of working systems that you can play with, from home computers to mainframes, as well as Bombes and the Colossus (used to break the Lorenz cipher), and WITCH. Very cool. https://www.tnmoc.org/

Quasi-related: If you're into old telephone switching equipment (some of which is computer-based), the Connections Museum in Seattle is not to be missed.