Carn Euny is an archaeological site near Sancreed, on the Penwith peninsula in Cornwall with considerable evidence of both Iron Age and post-Iron Age settlement. Excavations on this site have shown that there was activity at Carn Euny as early as the Neolithic period. There is evidence that shows that the first timber huts there were built about 200 BC, but by the 1st century BC, these had been replaced by stone huts. The remains of these stone huts are still visible today.
Carn Euny is best known for the well-preserved state of the large fogou, an underground passageway, which is more than 20 metres long. This fogou runs just below the surface of the ground and is roofed with massive stone slabs.
The site was abandoned late in the Roman period.
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.