It all depends on what interests you. If you are into shopping, Kings Road is a must. Changing of the guard, Big Ben, afternoon tea (at the Ritz), Harrods, St. Pauls (whispering gallery),if you like theatre the Globe theatre is a must. The Tower of London, the crown jewels.

If you have any ancestors from these areas I would highly recommend doing a little geneology while you are visiting. You may find some relatives.

I did my junior year abroad in Edinburgh and I think it's a fantastic city. Definitely check the castle out if you're into touristy stuff - I could see it from my bedroom window there and it was super cool. There's also a whiskey distillery that does tours and tastings. We also did a "Haunted Edinburgh" tour that takes you down back alleys and whatnot, talking about creepy history. That was fun. I'd also recommend just spending an evening at least in a pub - there's live music everywhere, including some traditional Scottish and Irish music, and the locals are very fun and warm.

At least, that's how it was in 1998 lol.

Even if you don't think you like theatre try it out. I always buy the cheapest tickets at the box office just before the show starts.

London theatre is amazing. Makes NY look like high school drama club.

Shopping is not so great as everything costs so much these days.

Will you have any time to get out of the cities and see some of the countryside? It's so beautiful, like a fairy tail.