The University of Cambridge (England) has invited graduates of the Australian National Unviersity to visit Cambridge in July to help celebrate the 800th Anniversary of the university. There is a week's program of talks and events organised at Madingley Hall, home of the Institute of Continuing Education, which has a garden by 'Capability' Brown), but I thought I would suggest a few of my own, based on a couple of visits to the Unviersity and its environs.
The first tip is to take with you, borrow or hire a bicycle (the basement of Kings College has some bicycles which look like they were forgotten a hundred years ago). I took my own folding bicycle on one visit and found it a very practical way to get around the city centre. There are bicycle paths by the river and some of the one way streets have a bicycle lane in the reverse direction.
There is an excellent double-decker tour which covers the inner city and also gets out to the countryside around Cambridge. The locals frown on this sort of tourism, so best to quietly go off and do it by yourself. One place the tour stops is the Cambridge American Cemetery and Memorial at Madingley.
A walk along the banks of the River Cam at dusk is a must. Time it right and you can see the choir crossing the bridge to King's College Chapel for evensong at dusk (also worth attending). A punt on the river is entertaining, but the river gets crowded with tourists, so if possible get an invitation to use a college punt from their own private lawns instead of the tourist punts.
The Cambridge University Press Bookshop is worth an half hour browse. There are numerous research organisations and companies clustered around the university facilitates. Do some research before you go and get an invitation to visit. Microsoft's research institute was interesting, but you need and invitation.
Lunch or dinner at "high table" is entertaining (skip breakfast it is not very good in the average college). The high table is where the college elite and guests sit, a few cm above everyone else. Just be careful to sit where you are told and be ready to explain what you do and be able to drop some names. Trinity College puts on a good lunch and King's College was good for dinner.
The Cambridgeshire Guided Busway has not yet opened (so Adelaide's O-Bahn Busway is still the world's longest) but you can take a ride on the test buses.
By the way if you aren't an ANU alumni, but have some academic connections, you may be able to talk your way into the colleges. Just look for someone you know, who knows someone at Cambridge. I found that with a Linked in search there were 111 people I was connected with, who were Cambridge graduates, 12 of whom live within 40 km of the university and 3 who work or research at it. Also keep in mind that the university is just a loose consortium of colleges, who are always looking for guest speakers from faraway places. Even if one will not let you in the door, another may well. Once I had one introduction, I found that opened other doors.