About the model
Late Neolithic passage tomb on Anglesey (Burrow's radiocarbon model: built 3074-2956 cal BC) with an east/north-east-facing stone-lined passage, roughly aligned on the midsummer sunrise, leading to a polygonal chamber of large slabs with a free-standing rounded blueschist pillar. It overlies, or is enlarged from, an earlier phase with an encircling ditch (c. 21 m across) and an inner ring of stones, usually read as a henge with a stone circle; whether there was a henge (outer bank) is debated. A ring of kerbstones c. 26 m across marks the edge of the final mound. Five Mesolithic postholes lie in front of the entrance. Excavated by W. J. Hemp in 1928-29 (Ministry of Works guardianship from 1923), after which the mound was rebuilt only around the passage and chamber: the modern mound is much smaller than the original, leaves the back of the chamber open to the air, and is held up in part by concrete roof supports. The carved Pattern Stone, found lying flat by the central pit behind the chamber, is in Amgueddfa Cymru (St Fagans); a cast stands upright behind the chamber near where it was found. Quotes are exact text of the cited pages (whitespace normalised); 'derived' marks values computed from quoted numbers or OSM geometry.