We did one of those hop-on/hop-off double decker bus tours on the Friday after we arrived, which was actually a pretty efficient way to see the 'main sights' of the city. So we managed to drive by Buckingham Palace, Westminister Abbey, Parliament and Big Ben without actually having to stand and walk in front of them. We did stop off at the Tower of London, though, which was huge and full of intrigue. Our tour guide who led an enormous group of us around the place was well-practiced in his speech and was a little hammy, and delivered on grisly details on executions, thank you very much. And there were a lot. I particularly liked the fat, giant ravens that wandered around the grounds. The myth goes that if the ravens leave, then the Tower falls. I found out later that their wings are clipped.