Must-sees in Oxford?

We're doing a short break on a narrowboat on the Oxford canal next weekend (yay!) and we will have most of Monday to wander around Oxford. I have a few ideas of what to see, but I'd love some suggestions as well.

Hm. The Pitt Rivers Museum is closed at the moment, and the Ashmolean is undergoing serious construction work, so bits and bobs of it are closed. It depends on what you're into, really. Some colleges are open to just walk into, some are closed, some (like Magdalen and Christ Church are fee-based.) In the past I have enjoyed joining friends on the Bodleian Tour (that's Oxford's library) and on on a tour put on by Boswell's bookshop. (Both on Broad St.)

Sheesh, I live here, you think I'd come up with more stuff. 

Oh, and you mean that you'll be in Oxford on the 8th, there's the St. Giles fair, which is your typical fair with fired foods and rides, in the centre of Oxford.

If you take one of the tours of the University make sure it includes Christ Church College. You will learn a lot more on a tour than you would just wandering around.

If you do a tour Don't do a bus tour, make sure it is a walking tour of the city.  You'll enjoy it so much more and see so much more and often you'll get into at least 1 or 2 of the colleges.  We used to go on them fairly regularly when people visited as it's not that far from us.
You could try going for a punt on the river.
The botanic gardens are pretty nice to visit.

Thanks for the suggestions! We ended up going down to Folly Bridge, walking around Christ Church Meadow, going to Alice's Shop, climbing Carfax Tower, wandering through the Botanic Gardens (gorgeous!) and walking back through the fair. I wish we'd had more time--so much to see! But we'll be back, I'm sure.

I was surprised to find a Krispy Kreme tucked in to Oxford Castle  when we visited.  It was quite strange seeing a modern American donut shop at the rear of a medieval castle.  It was also kind of sad to see in such a historic location.

I was surprised to find a Krispy Kreme tucked in to Oxford Castle  when we visited.  It was quite strange seeing a modern American donut shop at the rear of a medieval castle.  It was also kind of sad to see in such a historic location.

Just like seeing a Starbucks right in the middle of the Forbidden City in Beijing!!  That was really sucky to see, especially considering there aren't other shops in the place!