University of Sheffield

I have been visiting some Universities lately with my son as he is in the process of deciding where he wants to apply to. I keep hoping to get to visit some libraries while I'm there but have not been very successful as yet. This is because either the campus tour doesn't take us in the library, we don't have time or Ben insists that I don't wander off being an embarrassing parent by nosing around the library.
We went to Sheffield a couple of weeks ago and liked it especially the Students Union and the mixture of old and new buildings. We were shown round by a post grad student and the last stop was the library which he said was the 'jewel in the crown' etc. etc. So I thought great. We got to the entrance .....and that was it. He said it wasn't possible to look round and just pointed at things from the entrance. So I don't know why - whether it was because the library doesn't admit visitors or whether he didn't want to take us in - but it would have been interesting.