I think by "open" we are not talking about hours here, but the fact that a non-MIT student can walk in off the street, wander the halls, use the libraries, and study in a classroom.
Waterloo is mostly that way as well. Classroom use is tricky - there tends to be lock up at night after cleaning staff go through, but outside of the research labs, there aren't many controlled access areas.
Though a case can be made that this is mostly irrelevant in Waterloo's case, as for all intents and purposes, everyone in Waterloo who might be interested in what Waterloo has to offer is a student at Waterloo.