Nesebar, Bulgaria
8th century BCE
Veliko Tarnovo, Bulgaria
12th century
Vidin, Bulgaria
10th century AD
Belogradchik, Bulgaria
14th century
Kavarna, Bulgaria
14th century
Ivanovo, Bulgaria
11th century
Sofia, Bulgaria
16th century
Shumen, Bulgaria
7th century AD
Veliki Preslav, Bulgaria
9th century AD
Provadia, Bulgaria
10th century AD
Silistra, Bulgaria
1841-1853
Veliko Tarnovo, Bulgaria
12th century
Sliven, Bulgaria
4th century AD
Tervel, Bulgaria
6th century AD
Sevlievo, Bulgaria
10th century AD
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.