A very nice tourist attraction, there is a lot of historical stuff to see, everything is well explained and there are also imaginary stories set during the roman ages which you can listen with the audioguide and create the atmosphere of the first century.
Grantchester is a tiny village near Cambridge, actually beside a barrel race on the boxing day and Red Lion pub there is not much to see around. However the path that from Trumpington road leads to Grantchester is lovely, can be done in about 40 minutes walk but some alternative walks in the sourrounding fields are available too.
Oxford is a town similar to Cambridge for many aspects, but also quite different. It is bigger, you can feel more the athmosphear of movies like Harry Potter, it is colder and wetter. I enjoyed a lot my trip to Oxford but maybe I prefer Cambridge as a place to live in.
I have been to Salisbury for just a day. I enjoyed this tiny town, with a huge cathedral, a small city centre full of pubs and a relaxing walk along the river and a local italian restaurant where a waiter was tring to learn Italian!
Tower of London
I have not been inside the Tower of London so I have not that much to say about it. The area of London where it is located is called the City, or at least is very close to it, so in few hours you can see the Tower of London, the London Bridge and the St.Gills Cathedral...a real immersion!