OFF TO THE RACES. Today, Sultanahmet Square is a bustling tourist destination in Istanbul’s historic center. In ancient times, this area was also bustling, but for a different reason: horse and chariot racing. The square was originally a hippodrome built by Emperor Septimius Severus in 203 and renovated by the founder of Constantinople, Constantine I, in 324. Various Byzantine emperors adorned the hippodrome with impressive monuments from across the ancient world, including a red granite obelisk from the Temple of Karnak in Egypt that dates to the time of Thutmoses III (15th century BCE), and a fifth-century BCE bronze column (popularly known as the Serpent Column) that was removed from the Temple of Apollo at Delphi in Greece.