Interesting story but I have a bit of anecdotal evidence to share. Back when I was a Freshman at UIUC in 1989, I was given a campus tour and told that one of the buildings there was designed to collapse outwardly in order to protect the equipment in the basement. That equipment was a national computer network (not yet called the internet!)
So at the very least, the origin of this story predates 1991 by at least two years.
I don't recall the name of the building but here it is on Google maps.
Edit: It's not clear from my original comment but the reason for collapse would presumably be a nuclear strike. I remember this because this was a time when we grew up with a constant fear of a Russian nuclear strike and I couldn't help but wonder why anyone on earth would want to nuke Champaign.
Edit: Ah, here we go! It is the Foreign Languages Building (FLB), later renamed. I remember having to trudge here at 7ams on snowy winter days to listen to Japanese language cassettes.
I was going to share this story but you beat me to it. They're still claiming this in tours ~2017.
The building was called the Foreign Languages Building until very recently and is now called the Literatures, Cultures & Linguistics Building.
Relevant info from the UIHistory site:
"Located on the site of the former Old Entomology Building, ground was broken on the Foreign Language Building (FLB) on December 18, 1968.
A popular myth is that the building's distinctive architecture was a result of its being designed to house a supercomputer on campus called Plato. The building was supposedly designed so that if it was bombed, the building's shell would fall outwards, protecting the supercomputer on the inside. It is also rumored that the building's interior layout was a result of trying to confuse Soviet spies and prevent them from stealing secrets from the supercomputer.
In reality, the building's architecture is not actually all that unique and was a popular style of the day. In fact, just a few blocks to the west, one may find the Speech and Hearing Sciences Building, which a 2-story clone of the building. Plato itself was real, but refered not to a secret government program, but rather to the first "modern" electronic learning system, the forbearer of course software like WebCT and Mallard. The mainframe computer that ran the Plato system was located in north campus, in a building which used to reside on the west side of the Bardeen Quad." [0]
Plato was in fact real... I used it many times! Looking back, it was pretty impressive technology for its day but was quickly becoming obsolete. I hated having to walk all the way to campus to get some physics units in that I missed.
I vaguely seemed to recall that sometime around the Gulf war, I was able to modem in and connect remotely. Shortly after, I stopped getting Plato assignments!
Plato was an early interactive learning system, the supercomputer was called the Illiac-IV.
The building was called the "Center for Advanced Computation". I don't know if the computer was in that building, but I don't think they were exactly hiding it from the Soviets.
It's not easy to make things stay waterproof after such an event. Water will find a way. The simplest thing will likely be the Achilles heel of such thoughtful engineering.
It doesn't mean that should stay there, as-is, forever. Like most failover solutions, it gives you a bit of time during an incident to come with a proper solution for the future.
Having it not fully waterproof (and maybe they also took that into account) has probably been seen as an improvement over totally crushed by rocks and bricks.
So at the very least, the origin of this story predates 1991 by at least two years.
I don't recall the name of the building but here it is on Google maps.
https://www.google.com/maps/@40.106201,-88.2268272,3a,75y,91...
Edit: It's not clear from my original comment but the reason for collapse would presumably be a nuclear strike. I remember this because this was a time when we grew up with a constant fear of a Russian nuclear strike and I couldn't help but wonder why anyone on earth would want to nuke Champaign.
Edit: Ah, here we go! It is the Foreign Languages Building (FLB), later renamed. I remember having to trudge here at 7ams on snowy winter days to listen to Japanese language cassettes.
https://uihistories.library.illinois.edu/virtualtour/maincam...
Edit: And here's a contemporary article about the FLB, which also cited some of the crazy rumors about this building.
https://imgur.com/HXenjnt.png