Bryn Celli Ddu is a prehistoric site on the Welsh island of Anglesey located near Llanddaniel Fab. Its name means the mound in the dark grove. It was archaeologically excavated between 1928 and 1929. Visitors can get inside the mound through a stone passage to the burial chamber, and it is the centrepiece of a major Neolithic Scheduled Monument in the care of Cadw. The presence of a mysterious pillar within the burial chamber, the reproduction of the 'Pattern Stone', carved with sinuous serpentine designs, and the fact that the site was once a henge with a stone circle, and may have been used to plot the date of the summer solstice have all attracted much interest.
Bryn Celli Ddu is generally considered to be one of the finest passage tombs in Wales. Its passage and burial chamber are complete, and it is still buried under a mound or cairn. As it now stands, the passage is 8.4 m long, the first 3.4 m being unroofed with a pair of portal stones. The main passage has walls of vertical rock slabs, roofed by a series of stone lintels. The mound, being substantially smaller than as originally made, no longer completely encloses the burial chamber, so the back wall is open to the air, allowing some natural light in.
Free-standing inside the burial chamber is a smooth pillar of blueschist, a metamorphic rock, some 2 m high, with a very rounded shape.
The earliest identified remains at the site are a row of five postholes previously thought to have been contemporary with the tomb. Radiocarbon dating of pine charcoal from two of the pits showed these to date from around 4000 BC, putting them at the end of the Mesolithic, 1,000 years before the next phase of use.
In around 3000 BC a henge monument was constructed. An outer circular bank and ditch would have defined the boundary, although only the ditch survives, some 21m across. Within this, a stone circle would have provided the focus for a site of ritual significance. A ring of 17 stones formed an oval, many being in matched pairs either side of the centre.
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.