What are the best physics departments to do graduate work in theoretical physics?

Answer 1

If you're considering this, you probably already have an idea of what area of physics interests you. Look at the literature and see where this work is being done. Think about someone in the field you'd like to work with. At MIT, they won't let go of you until you really understand what's going on, and know how to think about it. That's of immense value. I'm biased, but it's true.

Answer 2

Cambridge - especially DAMTP

MIT