There is of course much, much more to see in London: Buckingham Palace, Westminster Abbey (pictured above), Covent Gardens, the huge London parks..
Take a self-guided walking tour with the help of a guide-book, or perhaps sign up for an escorted Walking Tour. My son and I took one about Ghosts of London, led by a personable and enthusiastic guide. (If you have young kids and want to do a walking tour, be sure to verify what ages are allowed to participate.)
-continue to Day Trip to LEGOLAND Windsor