I recently had the opportunity to tour the National Institute of Standards and Technology library, museum, and archive in Gaithersburg, MD. Unfortunately, I did not take any pictures on the tour. Here is a picture of the external building from the NIST library website:
The library building also houses a museum collection with artifacts from NIST history, such as the official meter stick, and the very first neon sign. The library staff has developed a digital museum with collections, as well as photographic representations of museum artifacts. The current featured collection is Standardization of Women's Clothing. See their photo gallery for collections of photographs from the museum collection.
The NIST campus is not open to the public, however some access to NIST publications is available through request from the website. Requests to visit the museum are granted in special cases. See the Library FAQ section for more information. The library does offer a vast amount of information about the collections through their virtual library portal. The library is an amazing collection of scientific research and technology information. The collections are primarily for use by staff, however the reference librarians may respond to information requests, or direct users to publicly accessible resources for information.
The campus itself is also interesting, in that it is a secure facility that has become somewhat of a nature preserve. The grounds are kept fairly natural, and contain numerous deer and other wildlife. In 1966 when the agency moved to the Gaithersburg campus, a direct decedent to the famous Apple tree which inspired Sir Issac Newton. I'm told the apples taste a bit mealy and aren't very good.