One of the best ways to see London is on a double-decker bus tour. You sit back and relax as famous site after famous site rolls by, accompanied by an informative commentary. If you fancy seeing more, you can hop off and on at your leisure anytime within a 24-hour period. Remember that open-topped means open to the weather, so if you want to stay up top, take a raincoat. Also, the streets get very congested, so you might find yourself gazing at a not-so-inspiring office block until the traffic jam below clears.