A day trip to Oxford was well worth it. Trains are inexpensive if you go during off-peak times. The city is incredible - such history and architecture. Be sure to tour Christ Church College - the dining hall is where Harry Potter was filmed. Very busy on weekends - so try to go during the week. Also, you don't really need to take a bus tour here, the train station is close to town and everything is in walking distance.

With the beautiful and varied architecture of its many colleges and a rich history, Oxford is worth the day trip (about one hour by bus) from London. You can pick up the bus at the Marble Arch Underground. Once there, you should probably join one of the many tours available. While the tour guides weren't particularly impressive, the tours do take you through the gates of colleges that the lone visitor would not have access to. Be sure to check out the Ivory Towers that have given university life their name. Overall, the university, and the town itself, are a wonderful place to spend a day.