The statue was commissioned from the artist by the Milanese Duke Ludovico Sforza in 1482. Leonardo made preliminary sketches and created a clay model. But as war broke out in 1499 he was forced to leave the city and his horse ended up as a huge target for French archers.
The donation to Milan is the culmination of a dream of the late Charles Dent, an American pilot. On reading the story of the horse 20 years ago, he vowed to see it made.
A passionate art lover, he sold much of his private collection to finance the project but died before it was realised. The Leonardo da Vinci's Horse Foundation, which he set up, completed the task of raising the $6m (pounds 3.75m) needed to cast the bronze.
Nina Akamu, a Japanese-American sculptor, made the 15-ton, 24ft-high bronze. Seven hundred members of the foundation crossed the Atlantic for the event. But Milanese reaction has been tepid. Few of the city's cultural heavyweights were present at the handover ceremony.
Some are touched by the dedication of Mr Dent and his supporters. Others dismiss the monumental piece as unwanted kitsch that would be more at home in Disney World.