Rona, a remote Scottish island, is said to have been the residence of Saint Ronan, Abbot of Kingarth in Bute (died 737). A tiny early Christian oratory which may be as early as this date, built of unmortared stone, survives virtually complete on the island. The site of one of the most complete Early Celtic religious complexes in Scotland. North Rona was abandoned after the Viking raids, but resettled by a secular community in the 12th or 13th century. Disasters, such as the drowning of the island's entire male population, and starvation brought about by a plague of rats, resulted in only intermittent occupation during subsequent centuries; the last resident, Donald Macleod, left in 1844 . North Rona is now a National Nature Reserve with Sula Sgeir.
Sited on a terrace within a thick-walled, oval burial enclosure, Teampall Rònain was probably a hermitage offshoot from the church at Europie in Lewis. It is two-chambered, the almost subterranean corbelled eastern cell being the late 7th/early 8th century `oratory' of St. Ronan, beautifully constructed with inward-leaning walls bridged over with stone slabs, traces of lime mortar still clinging to the sides. On the west wall, a door with slit window above leads into the 12 th-century chapel, its west gable still standing to six or seven ft. A stone-paved doorway was uncovered by Dr. Frank Fraser Darling on the south wall during his repair works here in 1938. He also excavated the east end of the earlier structure, unearthing the base of a stone altar and wall niche. Numerous Early Christian and medieval incised cross slabs lie on the site.
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.