The ancient chariot-racing ground that was the sporting and political heart of Constantinople for a thousand years. The track itself is long gone — the modern Sultanahmet Square sits on top of it — but three monuments survive along its spine: the Egyptian Obelisk from Luxor (3,500 years old), the Serpent Column from Delphi, and the rough-hewn Walled Obelisk. Stand at the southern end and try to imagine 100,000 spectators.