The square in front of the Blue Mosque was the Hippodrome of Constantinople, a chariot-racing arena that held around a hundred thousand spectators. The track is gone, but its shape survives in the outline of the park, and three of its monuments are still standing where they were placed.
The Obelisk of Theodosius is the oldest: carved in Egypt around 1450 BC for Thutmose III, brought here in 390 AD, and still sharp enough to read. Beside it stand the bronze Serpent Column, taken from Delphi, and the Walled Obelisk, whose plates were stripped during the Fourth Crusade.
The square is open at all hours and free. It is at its best early, before the tour groups arrive, when the mosque and Hagia Sophia face each other across an empty space.
From Hotel Sultania it is about ten minutes on foot.