Britain's Olympic and Paralympic stars gathered for their Beijing victory parade through London.
Chris Hoy, triple Olympic cycling champion in Beijing, said it was a "great way to say thank you" for all the public's support since the games.
Double Paralympic swimming champion Ellie Simmonds, 13, and 14-year-old diving sensation Tom Daley had the day off school for the big occasion.
Hoy said: "It is the day that the athletes have been waiting for. It is going to be massive and it is a chance for us to say thank you to the public.
"Back in Beijing we were away from how all this was being received in Britain and now we have the chance to give them a wave face-to-face and say thank you."
Cyclist Victoria Pendleton, 28, who took gold in the sprint, admitted she was "very excited" as she had not taken part in a parade since she was in the girl guides.
She said: "I'm really excited. I'm treating this as a social event. It is a chance to catch up with everybody from the different sports and get their news.
"This is my first parade that I have had since school. I remember that when I was in the girl guides there was a special parade in our village and I was dressed as a Tour de France cyclist in a cycling jersey - that was really fun and important at the time, but this is much more fun."
She said she had been "thrilled" about the public's support for all the athletes, but added: "It is four years to the London 2012 Olympics and I think people will get tired of us; I'm sure and things will go back to normal.
"We will put our medals back in their boxes and everyone will be back to training."
Daley said: "This is a pretty big day really and the school lets us off if we have a big day."
Standing next to Hoy, he said: "Definitely seeing Chris here with his three medals is a great inspiration for the future and hopefully I will be able to go out and get one for myself.
"It is amazing.
"I'm missing maths and Spanish at school today but this is really worth it.
"I saw the parade after Athens 2004 and it was really inspirational."
Simmonds said: "I went to Beijing just for the experience.
"I got two gold medals and have just been numb.
"It was amazing and it is wonderful to be in this parade. It is really exciting."
Paralympic rider Lee Pearson, who is now a nine-time gold medallist having picked up three more titles in Beijing, said: "I have never been in a parade before even though I have done three Paralympics.
"This is just very exciting.
"It is also great that so many people now seem to be getting behind and supporting Paralympic sport."
Team GB won 19 golds at the Beijing Olympics to finish fourth in the medal table with a haul of 47 medals - its best Olympic performance since 1908.
ParalympicsGB won 102 medals, including 42 gold, to finish second in the medals table behind the host nation, China.
Today up to 350 athletes, who will be on 12 floats, are set to be cheered on during the parade.
Well-wishers and sports fans are expected to flock to London as the parade sets off from the Mansion House and ends at Trafalgar Square.
Simon Clegg, the British Olympic Association's (BOA) Chef de Mission in Beijing, said: "This is a fantastic and historic day bringing together the most successful Olympic team for 100 years with their Paralympic colleagues to celebrate British success.
"It is a great way to celebrate and also to look forward to London 2012 in four years' time."
London Mayor Boris Johnson paid tribute to the Olympians, whom he described as "national heroes".
Mayor Johnson said: "It is a great honour and a thrill to stand in the shadow of Nelson and congratulate our current crop of national heroes, who did battle proudly and successfully in Beijing over the summer.
"Our athletes at this summer's Olympic Games and Paralympic Games are an inspiration to all of us and it is right that we salute them today as we prepare to host the next Games in this wonderful city of ours.
"I wish them well as they prepare for that challenge and encourage everyone else to support them and draw inspiration from their success."
Lord Coe, who won two Olympic golds, hopes Team GB's exploits in Beijing can act as a springboard for London 2012, of which he is the organising committee's chairman.
"The British success in China was exactly what the nation needed and I look forward to being part of the event and thanking those athletes for a wonderful summer," he said.
"The success of the team and the reaction of the British public this summer will be multiplied many times over in 2012 - I know the country will be transfixed by the London Games and I am sure that the athletes involved today will be firmly focused on the task ahead and the road to 2012.
"Equally, those who didn't quite make it to the Games this summer will be redoubling their efforts to reach the pinnacle of their sport - appearing at an Olympic Games or Paralympic Games in their home country in four years' time."
Triple jumper Phillips Idowu admitted he was disappointed after leaving Beijing with a silver medal but had now been inspired to go one better in London.
Idowu told the BBC: "I am feeling great now. I have had a really good time since I got back. I have had a really positive response from everyone.
"This is crazy right now. T
here is so much support for the team and we did really well. These are the guys that are inspiring me to go on to 2012.
"It's nuts! I can't believe it. It's like all of London has shut down."