Impressive Neolithic chambered tomb, with partially restored entrance passage and mound, on the site of a former henge monument.

Bryn Celli Ddu – the Mound in the Dark Grove – is probably the best-known prehistoric monument on Anglesey, and is one of the most evocative archaeological sites in Britain. Like other prehistoric tombs on Anglesey it was constructed to protect and pay respect to the remains of the ancestors.

First explored seriously 1865, the tomb was thoroughly excavated in 1928–29. The excavations revealed something of the long and complex history of the site.

The monument seems to have begun in the later Neolithic around 5,000 years ago, as a ‘henge’ or a ritual enclosure. It consisted of a bank (now lost) around an inner ditch, which enclosed a circle of upright stones. The ditch originally measured 21 meters in diameter. The outer edge can still be seen and several stones from the inner stone circle also survive.

At a later date, towards the end of the Neolithic, the henge made way for a passage tomb, a type of burial monument found around the Irish seaboard and as far afield as Brittany.

The Bryn Celli Ddu passage tomb consists of a long passage that leads to a polygonal stone chamber. Human bones, both burnt and unburnt, were found in the passage of the tomb. Other finds were few, but included quartz, two flint arrowheads, a stone bead, and limpet and mussel shells.

A decorated pattern stone has also been found at Bryn Celli Ddu. The stone was discovered near a ceremonial pit at the back of the chamber. A replica of the stone has been set up at the site.

What sets Bryn Celli Ddu apart from the other tombs on Anglesey, is that it is the only one to be accurately aligned to coincide with the rising sun on the longest day of the year. At dawn on midsummer solstice, shafts of light from the rising sun penetrate down the passageway to light the inner burial chamber. Perhaps this sunlight was meant to bring warmth and life to the ancestors?