Hi Max,
The Underground, or the Tube, is London’s rapid transit system—clean, frequent, and extensive, with zones and Oyster/contactless payments making trips easy. Tourists love red double-decker buses for their iconic look and great sightseeing routes, especially from the top deck with open air in good weather. Yes, you can take a taxi in London—licensed black cabs or ride-hailing apps are available, but expect higher fares.
Best regards, Alex