At about 40m long, Carlungie Earth House is one of the largest and most complex examples of its kind in Scotland. It was accidentally discovered during ploughing in 1949. Subsequent excavations during the following two years also revealed about eight associated stone dwellings at ground level.
Earth houses, or souterrains as they are also known, were not dwellings, but stone-lined underground passages which typically date to the Iron Age. They’re found along much of eastern Scotland, as well as in Ireland, Cornwall and Brittany.
References: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.