The Horses of Saint Mark, also known as the Triumphal Quadriga, is a set of bronze statues of four horses, originally part of a monument depicting a quadriga (a four-horse carriage used for chariot racing)
The horses were placed on the facade, on the loggia above the porch, of St Mark's Basilica in Venice, northern Italy after the sack of Constantinople in 1204.
They remained there until looted by Napoleon in 1797 but were returned in 1815.
The sculptures have been removed from the facade and placed in the interior of St. Mark's for conservation purposes, with replicas in their position on the loggia.

Information from Wikipedia