I would be surprised if this were true for MIT libraries, it certainly is not for Harvard. Otherwise, many academic buildings were open. But not libraries because tourists would be disruptive.
MIT's openness is a huge wedge issue in the Harvard-MIT culture wars. That sounds like stupid elitist junk, but makes since historically. MIT wasn't always... "MIT". Not too long ago, it was just another college. Its open culture combined with proximity to austere academic/government/private institutions is one of the two reasons that it grew to be the behemoth is it now. The literal openness to the public has long been a huge source of "soft power" for MIT.
(The other reason for MIT's rise being WW2 and the military-industrial-academic complex ofc)
Even with this topic set aside, MIT has been turning into just another Harvard, which is a real shame. MIT alum used to be very proud of the fact that any and all were welcome to participate in many aspects of campus life.
the other other reason for MIT's rise was its acceptance of Jewish scientists fleeing Germany in the pre WWII period, while the ivy league schools* still had (anti) Jewish quotas.
also, MIT was not a complete slouch before that, as Harvard proposed absorbing MIT in the early part of the 20th century.
* which weren't technically ivy league yet, that league being found in 1954
Interesting. My own alma mater UCL was founded on openness to women
and Jews and has thrived on that ticket of inclusivity. It was early
to the table in admitting overseas students when most UK universities
only recruited provincially.
When visiting central London I sometimes feel like a walk around the
Gower Street quad, and seem able to mooch about the campus and poke my
head into familiar lecture halls - even though it's central London
location would seem to make theft/vandalism a threat.
I think a lot of this physical security lockdown nonsense is
post-pandemic culture, and obviously the profitability of "security
industries"
pre-covid, you could go into MIT libraries as a member of the public. This was well known in Cambridge exactly because it was in stark contrast to the policy for Harvard libraries. You also could get on the wifi and access all the journals MIT had electronic access to.
The MIT library is open to anyone who can get into the cluster of buildings that contains it (along with the main building, the infinite corridors, math and CS and many other disciplines). You won't be able to check out books if you aren't from MIT, but you can stroll and read and scan at your pleasure.
Public libraries allow anyone in -- BPL for example. I used to study there all the time, but I didn't think it was that disruptive. This is just one opinion but I actually really like this as a heuristic and will probably use it myself. Libraries should be open to all!