Introduction to Sultan Ahmet Square: Located directly in front of the Blue Mosque, it is the Byzantine-era chariot arena and the ancient "Hippodrome" in the civic center. There are the Obelisk of Theodosius, the bronze Serpent Column and the Obelisk of Constantine in the square. The remains of the crescent-shaped walls of the Coliseum can be seen on the southwest side of the three monuments. There are 18th-century wooden houses around the square, which are very eye-catching and are now used as small hotels or libraries that collect books about the city of Istanbul.