Walls of Constantinople

City walls of Constantinople (modern Istanbul, Turkey)

The Walls of Constantinople are a series of defensive stone walls that have surrounded and protected the city of Constantinople 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.

This keyword could refer to multiple things. Here are some suggestions: