Some of the biggest Olympic and Paralympic stars are marking one year on from London 2012 with the Anniversary Games this weekend.
Three days of athletics are taking place in the Olympic Stadium in east London from Friday to Sunday.
We run down some of the big names to look out for...
Usain Bolt and James Dasaolu
The fastest man on the planet Usain Bolt is in the 100m on Friday at 21:48.
He's taking on rising British star James Dasaolu, who became the second fastest man in British history earlier this month when he ran 9.91 seconds at the British Championships.
Bolt may be the 100m world record holder, but his fastest time this year is only 9.94 seconds!
Mo Farah is taking part in the 3,000m on Saturday at 16:32.
He'll be hoping to win again on the same track where he triumphed in the 5,000m and 10,000m last summer.
In a survey of children commissioned by Newsround, Mo came out as the most inspirational Olympian of London 2012.
Heptathlon champion Jessica Ennis-Hill was the poster girl of London 2012.
She is competing in two events - the 100m hurdles and long jump, on Saturday at 14:11 and 15:50.
Jess, who got married in May, has been hit by injury problems with her Achilles recently.
Jonnie Peacock will be hoping to repeat his Paralympic gold success in the T43/44 100m on Sunday at 17:01.
He's on good form - having just taken the world title in France earlier this week.