If undertaking a walk around Heathrow, allow at least four hours. Be prepared to walk where there is no pavement, and where you are patentely unwelcome. Heathrow Airport is a huge tract of land. Thousands of acres, hundred of buildings, and vast space for the manouvering of aircraft.

In 2026, walking between terminals at London Heathrow (LHR) is highly restricted due to the airport's massive layout and the placement of the runways. You can only walk between Terminal 2 and Terminal 3, which are connected by a well-signed pedestrian underpass; this walk takes about 10 to 15 minutes. For all other terminal transfers (e.g., T2/3 to T4 or T5), you cannot walk and must use the Heathrow Express or Elizabeth Line trains, which are free for travel between terminals (provided you tap a contactless card or Oyster, though no charge is applied). Within the terminals themselves, there is extensive walking required to reach "B" or "C" satellite gates—for instance, the walk to T5C can take 20 minutes. Heathrow has maintained its status as a "mega-hub" in 2026, so unless you are transferring between the "Central Terminal Area" (T2 and T3), you should rely on the automated track transit systems or buses rather than attempting a journey on foot.