The Tregiffian Burial Chamber is a Neolithic or early Bronze Age chambered tomb. It is a rare form of a passage grave, known as an Entrance grave. It has an entrance passage, lined with stone slabs, which leads into a central chamber. This type of tomb is also found in the neighbouring Isles of Scilly.
The large stone grave, half of which was covered by a road in 1846, was, unlike Cornish quoits, for the most part covered with soil, with only the entrance exposed. From the edge of the site a passage, covered by four 3 m long stones, led to the 4-metre deep grave chamber. In front of the chamber, a cross-lying ornate stone, with cup-and-ring markings, formed a barrier. The original stone is in Truro, in the Royal Cornwall Museum, the local stone is a replica. Inside the tomb there was the chamber grave, which consisted of upright stones and a cover slab. Tregiffian probably formed a holy place with the Merry Maidens and other sites.
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.