Short answers, pulled from the story.
The original Horses of Saint Mark are displayed inside St Mark's Basilica in Venice. They were moved indoors in the early 1980s due to damage from air pollution. Replicas now occupy their former position on the loggia of the basilica's facade.
The exact date is disputed. Many scholars date them to the 2nd or 3rd century AD, citing similarities to the Equestrian Statue of Marcus Aurelius (c. 175 AD). Others argue for Classical Greece, placing their creation in the 5th or 4th centuries BC.
Napoleon had the horses forcibly removed from St Mark's Basilica in 1797 and transported to Paris, where they were used in the design of the Arc de Triomphe du Carrousel paired with a quadriga. They were returned to Venice in 1815 following his final defeat.
Captain Dumaresq, a British officer who had fought at the Battle of Waterloo, was selected by the Emperor of Austria to return the horses to Venice in 1815. For his skillful handling of the task, the Emperor gave him a gold snuff box with the Emperor's initials in diamonds on the lid.
Analysis shows the Horses of Saint Mark are at least 96.67 percent copper, making them more accurately described as impure copper rather than true bronze. The low tin content raised the casting temperature to between 1200 and 1300 degrees Celsius.
The horses were long displayed at the Hippodrome of Constantinople as part of a quadriga. They were looted by Venetian forces during the Fourth Crusade sack of Constantinople in 1204 and installed on the facade of St Mark's Basilica in 1254.