The rings, which measure 12 metres in width, the same as a double-decker bus, will be seen by an estimated two million passengers travelling through Heathrow.
Former Olympian Mark Foster was present to unveil the rings this morning, he said: “I know first-hand the nervous excitement that every athlete feels when they arrive for the Olympic Games.
“The atmosphere is electric and often the airport is the first time we see fans and really feel the special buzz of the weeks to come. The rings will create a huge sense of excitement and be a great part of the welcome for everyone travelling through the terminal.”
Other sets of giant rings are being installed at various iconic sites all over the UK in preparation for the games.
London 2012 chief executive Paul Deighton said: “The Olympic rings are an iconic symbol, inspiring athletes and uniting people around the world.
“To athletes they represent the culmination of thousands of hours of training and reaching the highest level in sport.
“As we welcome the world, these rings will excite and inspire visitors arriving at Heathrow.”