Walls, Gates, Towers, Pillars, Monuments

It is believed that the first walls were on the hill where Topkapi Palace is situated today. They have been collapsed leaving no traces behind. Emperor Septimus Severus had these walls torn down when he attacked the town. He had the walls made starting in Sirkeci and ending at Hagia Sophia. Remains of these walls have not been rendered either. Emperor Constantinus is one who has surrounded the city with walls for the third time. Gate of Jesus in Cerrahpasa is the only remain of these walls which remained to our days. These walls covered five hills of the city.
When population increased, new sections started forming outside the walls.Then, Theodosius II made the city surrounded with walls containing these new sections too (412). Walls start on the shores of Sea of Marmara and end on the shores of the Golden Horn. They are 5 km long and were strengthened with 110 towers. Of these Golden Horn walls, only those walls in the direction of the Sea of Marmara and of the land have remained to our day, around these walls, ditches and double walls are formed. Most important gate of the walls is the Porta Aurea (Gilded Gate) on the Yedikule walls (Sultan Mehmet "the Conqueror" had these walls repaired and extended in 1458). Walls destroyed in an earthquake, were repaired by Governor Constantinus in the period of Theodosius'. Heraklius had the north of the walls reconstructed in 627. Also in Leo V's and Manuel Comnenos' period repairs were made. The walls which Emperor Anasthase I had made between the years 507 and 511 outside the walls encircling the city are important. These walls start at Avcik quay and end in Silivri.
Genoeses living in Byzantium, although founded their own cities, have dominated Galatia. They dug trenches around the city and built high houses on the sides of these trenches in 1303-1304. Connecting these houses to each other with high walls, they formed the city walls. Beyazid II had the walls repaired but they were destroyed again in an earthquake (1509). These walls were repaired again in Sultan Murat IV's period (1635).Ottomans did not attach much importance to the walls, but by constructing towers in certain places, they have strengthened them.

Pillars
Hopped Column (Cemberlitas):Constantinus I had the pillar at the Temple of Apollo brought to Istanbul in 330 and made the Apollon statue situated thereon be replaced by his own statue. Later, each new emperor removed the statue of his predecessor and replaced it with his own. It is 40 meters high. Sultan Mustafa II, had the pillar reinforced with hoops for protection purposes (1700).
Obelisk (Dikilitas):It is known as the Obelisk of Theodosius I; it was erected in the Hippodrome in 390. It is 18.54 m high.
Snaked Column (Yýlanlý Sutun): It is on the Sultanahmet Square. It was dedicated in the Temple of Apollon by Greeks. Constantinus brought it to Istanbul in 390. It is 5.35 m high and resembles three snakes wrapped around each other.
Goths Pillar: It was erected following the victory against Goths. It is situated in the Gulhane Park. The pillar dates back to 4th century and is 15 meters high.
Arcadius' Pillar: It was erected in 421 for the memory of the victory gained against the Goths at Cerrahpasa in 403.
Maiden's Column (Kiz Tasi): It is in the township of Fatih; it is 10 m high made of granite. It was erected in the period of Emperor Marcianus (450-57).
Plait Column (Orme Sutun): Constantinos VII had it made in 944. It is 20.68 m high.

Monuments
Cabbage Monument: It is on the road descending from the right, at the entrance of Imperial Porte of the Topkapi Palace. It was ordered to be built by Selim III (1790).
Okra Monument: It is next to the cablage monument. It was caused to be built by Sultan Mahmut II in 1811 . Hadika (Fruit Orchard): It is located at the Kabatas Quay. In 1851, it was ordered by Sultan Abdulmecid to be built to symbolize the construction of the Kabatas Quay.