Sialia said:
Bodelian.
sigh.
And a lot of the other Oxford buildings. Without a student pass, no entry.
Well, the situation has changed somewhat in the past 5 years or so. There are a few more buildings open to the public, but taking a tour is pretty much the only way to see the Bodleian.
Almost all the colleges are open to the public, most of the time. But there are times when they are closed to visitors completely (and sometimes inexplicably). It's really hit or miss I guess.
If you're not spending several days just in Oxford, you may have trouble seeing everything you want to see since getting in some places really depends on flexibility. (Besides, you'd probably need a whole day for the Ashmolean and another day for the University Science Musuem/Pitt Rivers.)
On the other hand, if you've come to see the University, you have to remember that is is still a working institution. If a few tourists get inconvenienced because the students don't want to be disturbed in the Upper Reading Room, well, tough.
If it's any consolation, most students don't get to see
all of the Bodleian. They're restricted to the reading rooms (and some restricted to specific reading rooms). The majority of the bookstacks are staff only, as is the tunnel under Broad Street.