London: Buy an Oyster card or Travelcard for the Underground and buses

To save money and get discounted fares, purchase an electronic Oyster card at a Tube station for 3 pounds, charge it with a cash value, and use it on the Tube or on buses around the city. You reload it with money as needed. Another option is a Travelcard, sold for a specific number of days (even one day) of travel and good for buses and for specific zones in the Tube system. Buses are a good way of seeing the town, particularly if you plan to hop on and off to cover many sights—but don’t take a bus if you are in a hurry.