Secretariat at the Belmont Stakes in 1973 - his "tremendous machine" performance

YouTube link.

Everyone who watched the Belmont 40 years ago will never forget Secretariat's race that day.  He had already won the Kentucky Derby and the Preakness; this was his bid for the Triple Crown, and he was so good that few owners wanted to enter their horses against him in the Belmont - that's why there were only four racing that day.   The track didn't even take "show" bets, and it's an interesting (?unique) anomaly that Secretariat was so favored by bettors that he would have paid more to show ($2.40) than he did to win ($2.20).  Over 5,000 winning tickets were never redeemed because the holders valued them more as souvenirs than for their cash value.

And to this day his speed for 1.5 miles has never been equaled.  Even if you have no interest in thoroughbred racing per se, you owe it to yourself to watch this 3-minute clip to see one of the iconic moments in the history of sport.