How many walls protected Constantinople?

Constantinople was protected by a series of formidable walls, most notably the Theodosian Walls, which consisted of an inner and outer wall system. This defensive structure spanned approximately 5.7 kilometers (3.5 miles) and included towers, gates, and a moat. In total, there were three main layers of walls: the outer wall, the inner wall, and a moat, making it one of the most fortified cities in the medieval world. These walls successfully defended the city for centuries until the Ottoman conquest in 1453.