The Mên-an-Tol is a small formation of standing stones in Cornwall. It consists of three upright granite stones: a round stone with its middle holed out with two standing stones to each side, in front of and behind the hole. When seen at an angle from one side, the stones form a three-dimensional '101'.
The site probably dates from the late Neolithic-early Bronze Age (approx. 2500-1500 BC) as do the other stone circles in West Penwith, and was probably used for ritual and ceremonial purposes.
The two side stones are both about 1.2 metres high. The westernmost stone was moved and brought into a straight line with the other two stones sometime after 1815. The holed stone is roughly octagonal in outline. It is 1.3 metres wide and 1.1 metres high; the circular hole is 0.5 m in diameter. The only other holed stone in Cornwall of this type is the Tolvan holed stone which can be seen in a garden near Helston.
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.