Having lived in Mountain View, I can attest to the openness of Stanford.

The campus is fairly accessible. Including a number of seminars which are open to the public.

Other facilities, notably the library, not so much by reports.

yeah you can only get in with a student idea, and up to 7 times a year without one. I think it's a real shame because they have an amazing collection of up-to-date periodicals in there. Basically, any major newspaper & magazine from around the world is available the day after publication in the home country. Not sure how relevant it is in the age of ubiquitous online publications, but it's still nice. The green library also has a fabulous collection of old books.