Theodosian Walls

The Theodosian Walls are the fortifications of Constantinople, capital of the Byzantine Empire, which were first built during the reign of Theodosius II (408-450 CE). Sometimes known as the Theodosian Long Walls, they built upon and extended earlier fortifications so that the city became impregnable to enemy sieges for 800 years. The fortifications were the largest and strongest ever built in either the ancient or medieval worlds. Resisting attacks and earthquakes over the centuries, the walls were particularly tested by Bulgar and Arab forces who sometimes laid siege to the city for years at a time. Sections of the walls can still be seen today in modern Istanbul and are the city's most impressive surviving monuments from Late Antiquity.