OK, let's get one thing clear first, the answer to the most common question from people on a layover at Heathrow Airport.
There are no sightseeing tours that pick up from Heathrow or its hotels that will take you sightseeing into London, (or indeed anywhere).
If you want a public tour of London then you will need to take public transport into the centre of London and join the tour there or charter your own private sightseeing capability.
The full range of transport options between Heathrow Airport and Central London are laid out for you on our dedicated Heathrow Airport - Central London transfer pages.
By far the majority of people travelling between Heathrow and Central London for layover sightseeing use the London Underground, by far the cheapest transport option as well as taking you direct to the sights themselves.
Underground trains leave Heathrow about every 5 minutes throughout the day between about 5.30am and midnight, (slightly shorter times on Sundays).
There are 3 stations at Heathrow covering all 5 passenger terminals.
The most popular way of seeing London's sights in a short space of time are London's Hop on, Hop Off sightseeing buses.
There are three competing tour companies, for a discussion of the differences between them, read our dedicated page, Comparing London's hop-on, hop-off sightseeing buses.
Though note, you need at least 3 hours to do one lap of the main sightseeing route on these buses even without hopping on or off.
At this moment in time we would suggest Tootbus as being a good fit for those travelling in from Heathrow.
From Heathrow the Piccadilly Line of the London Underground stops at Gloucester Road, Knightsbridge, Hyde Park Corner and Green Park Stations in a journey time of between 30 and 45 minutes. Tootbus stops outside all of these stations.
Tootbus London Discovery tickets + Vox City guided walking tours
• Choose from 24, 48 or 72-hr tickets • Audio guide in 5 languages • 2 professionally guided walking tours: The Wizard Walk - Harry Potter Walking Guided Tour & The Royals and Landmarks - Walking Guided Tour
The least hassle and most straight forward way to get a good look at London's iconic sights from Heathrow is to let one of London's famous black taxi cabs and one of their equally famous cabbies show you around London.
The tour departs and returns to your hotel at Heathrow or passenger terminal and you decide where you would like to visit. Alternatively let your cabbie suggest an itinerary for you. Luggage can be carried as well. For full details of this opportunity, click through on the link below.
Black Taxi tour of London from Heathrow terminals and hotels
If your priority is to just find something more pleasurable than killing time between flights in an airport terminal then Windsor is a great alternative to London, it is very close to Heathrow. Public buses run from Terminal 5 frequently stopping outside Windsor Castle, but there is much more to Windsor and Eton than the castle.
If you have luggage we have a solution that takes care of that too.
Windsor stopover solution for Heathrow Airport - more details
We can customise a day to remember reflecting your interests and time available. We can offer solutions for one or two people with a friendly driver right up to a formal coach tour for large groups requiring a formal tour with top grade guides and attraction tickets included.
Full details at our Private tours from Heathrow page.