The Byzantine Walls refer to a series of fortifications that protected the city of Constantinople, the capital of the Byzantine Empire. Constructed primarily during the 5th century, these walls were designed to defend against invasions and included a complex system of towers, gates, and ditches. The most famous section is the Theodosian Walls, which were remarkably effective in safeguarding the city for over a thousand years. These walls showcased advanced military architecture of their time, featuring double walls with a wide moat in between. The Byzantine Walls played a crucial role in the city's defense until the fall of Constantinople in 1453, when the Ottoman Empire successfully breached them. Today, remnants of these walls can still be seen, highlighting their historical significance.