Walls of Constantinople
Construction of the Walls of Constantinople began under Constantine the Great, who enlarged the previously existing walls of Byzantium in order to defend the new Roman capital city which quickly grew following its proclamation as Nova Roma. A new set of walls was built further west during the reign of Theodosius II, and rebuilt after an earthquake in 447 in their current shape. The sea walls in the Seraglio Point area, which have continuously existed since Lygos and Byzantium, are the oldest part of the city walls; while the double land walls of Theodosius II at the western end of the city are the strongest parts. The northwestern section of the land walls was built in 627, during the reign of Heraclius (610–641), in order to accommodate the suburb of Blachernae, and added to by later emperors.