Schneier writes "Most people might not be aware of it, but there's a National Cryptologic Museum at Ft. Meade, at NSA Headquarters. It's hard to know its exact relationship with the NSA. Is it part of the NSA, or is it a separate organization? Can the NSA reclassify things in its archives?"
There's some interesting stuff in the comments about the building's reason for existence (window views a nearby NSA building?) and some stuff they have (an Enigma machine!).