The Column of Constantine is a monumental column commemorating the dedication of Constantinople by Roman emperor Constantine the Great on 11 May 330 AD. Completed c. 328 AD, it is the oldest Constantinian monument to survive in Istanbul. The column stood in the centre of the Forum of Constantine, on the second-highest of the seven hills of Nova Roma, and was midway along the Mese odos, the ancient city's main thoroughfare.
Ottoman repairs in c. 1515 added iron reinforcing hoops to the shaft. The column was consequently given the Turkish name Çemberlitaş (from çemberli 'hooped' and taş 'stone'), which also came to refer to the surrounding area.
Since 1985, the monuments of the historic areas of Istanbul, including the Column, have been listed as a UNESCO World Heritage Site.
The Walls of Constantinople are a series of defensive stone walls that have surrounded and protected the city of Constantinople (today Istanbul) since its founding as the new capital of the Roman Empire by Constantine the Great. With numerous additions and modifications during their history, they were the last great fortification system of antiquity, and one of the most complex and elaborate systems ever built. They were also the largest and strongest fortification in both the ancient and medieval world.
Initially built by Constantine the Great, the walls surrounded the new city on all sides, protecting it against attack from both sea and land. As the city grew, the famous double line of the Theodosian Walls was built in the 5th century. Although the other sections of the walls were less elaborate, they were, when well-manned, almost impregnable for any medieval besieger.