There are SEVEN FLoOrs?!?!?? I don't think I've actually been in a building with that many floors :/ let alone a hidden floor!
That sounds like the Chamber of Secret Beanbags! X'D the Art College library is empty most of the time, so I have the whole place to my self, which is nice because the main campus library is usually overcrowded with people waiting to get a seat :/ scary. The art school used to be jam factory, so there are huuuuuge minna-esque wooden beams in the walls and roof that you have to duck under and on hot days apparently jam starts to leak out of the walls O___O but it's a really nice cosy library.
Most of the floors are underground, for some reason. I think ground floor is... well, there's a bridge on one side, and lower ground beneath, but I think the bridge is at the fourth floor, so 2, 1, and sort of 3 are underground. His chamber of beanbags was destroyed by the elevator maintenance men, sadly. The nest is no more. Also, we have some weird people that hang out in the library. Some of them aren't students, and they take computer seats and make a ruckus.
I'd love it if we had a second, smaller library somewhere. As it is, we have to reserve study rooms at least a day in advance if we want to use them. That wooden beamy library sounds more up my alley than the concrete death fortress (with beanbags) that we have.
The library at my sister's college is nine floors and apparently has a doughnut hidden in a glass case somewhere that's been there for 34 years.
College libraries are interesting, when they have a century or two's worth of weird people who went there in the past.