Historians agree that these two beautiful columns are stolen property but don’t agree about who the Venetians took them from. They are called the Pillars of Acre (pili acritani) because for centuries, it was believed that the Venetians stole them in 1256 from the church of St. Saba in the port city of St. John of Acre in what is now Syria. They reside in front of what used to be the ceremonial entrance to the Basilica di San Marco, and most books describe them as exquisite examples of 6th century Syrian carving.
But recently, scholars have decided that they were really stolen from Constantinople in 1204 as part of the vast looting of the Fourth Crusade, and that they came to the Basilica in the same batch of plunder that included the Four Horses and the Madonna Nikopeia.
Who knows? They are certainly gorgeous. Those Venetian crusaders had quite an eye for beauty.