London is impossible to summarize.
It would be easy to write a book just on London’s top historical sights. For that matter, another entire book could be written on its best restaurants, or its most exciting nightlife, or its most intriguing artwork. No one needs to be convinced to visit London.
The only thing I think worth adding is this: London is best seen on its own, without including other parts of Europe within the trip. I’m not saying I’m opposed to adding in other parts of the U.K. to your trip, I just know how massive London is and how difficult it can be to see what you want to without feeling rushed.
We found that London bore more of a resemblance to New York or L.A. than it did any other place in Europe. We had just left Brussels and London felt a bit overwhelming. We had tried to fit too much into too little time. So take your time, and if you don’t have much time, focus on a few particular highlights. Don’t try to fit it all in. In the grand scheme of things, London is far easier to get to than Budapest or Zagreb. You’ll make it back!
For a brief overview of London’s finest, check out: London Town
For a discussion on buses v. the Underground, read: Public Transportation in London
To learn about Oyster cards and how they work, read: How does London’s Oyster Card work?