As a popular travel destination, Mexico City is served by many airlines that have a cheap flight available from London's Heathrow Airport. British Airways, Air Canada, Aeromexico and United all provide cheap, direct flights from London to Mexico. A direct flight takes about 8 hours. Flights from London-Mexico can also be arranged with stop-overs in any of the major airports on the American East Coast, Montreal or Toronto. The duration of the stopovers range from forty-five minutes to 24 hours so the adventurous traveller may take advantage of cheap flights while taking time to visit an extra city while waiting for the next flight. Transportation services from London to Heathrow airport are among the best in the world. Rail passengers can arrive at Heathrow from any tube station in Greater London, although not all trains connect directly and a transfer may be necessary. Heathrow can also be accessed by car or bus. The airport in Mexico City is less than five kilometres from the downtown neighbourhood and well served by both bus and taxi. The airport is extremely large and busy and travellers may find it convenient to refer to the displayed airport maps to locate the bus and taxi areas.