Dual Derby winner Harzand has been retired and will stand at the Aga Khan's Gilltown Stud in 2017.
Trained by Dermot Weld, the Sea The Stars colt overcame a late scare to win the Investec Derby at Epsom in June.
Having spread a plate in transit, he needed constant treatment in the run up to the race and showed great courage to hold off US Army Ranger.
It was then a rush to prepare him for the Irish Derby but he once again displayed a willing attitude to fend off Aidan O'Brien's Idaho.
His season ended with defeats in the Irish Champion Stakes, in which he suffered another injury, and the Prix de l'Arc de Triomphe, in which he finished ninth.
Weld told At The Races: "He's been a wonderful horse to train.
"I've enjoyed training him. He's won two Derbies for us. He's a beautifully-made colt, very sound.
"It's been a team effort. It hasn't been the easiest - when he spread the plate before Epsom it was nerve-racking - but it was his guts and courage that won the day.
"He then went on antibiotics as he picked up an infection after Epsom, but he came back stronger than ever to win the Irish Derby.
"He had a long year, a hard year. People forget he won his maiden by 16 lengths in March and then the Ballysax in April."
"He has done everybody proud and it's been an honour to train him."
Harzand won four of his seven races and was ridden in all of them by Pat Smullen.
Smullen said: "Epsom was nerve-racking, but when I cantered him to the start there was never a question of him not running as he felt great.
"After he won the Ballysax I said I didn't think he'd be suited to Epsom, but all spring he kept on proving me wrong, he kept on improving.
"That's just typical of very good horses - they keep on improving - and he gave us two great days.
"He got struck into at Leopardstown which meant his race was over and that made it a rush to get him ready for the Arc. Maybe it just came too soon.
"That was unfortunate. He won his maiden by 16 lengths in April so he'd been on the go a long time, he was exceptionally good in both Derby wins.
"Hopefully he'll go on to prove Sea The Stars as the sire of sires."
