Bryn Celli Ddu is a Neolithic burial chamber located on the island of Anglesea near Llanddaniel Fab.
The burial chamber was excavated in 1928/9 by W J Hemp. He found the 'Pattern Stone' in the tomb, which has since been removed to the National Museum of Wales and replaced with a replica.
A ring of kerbstones marks the boundary of the original mound, following the line of a ditch from an earlier henge monument. Three stones are visible within the mound and are thought to be from the original henge.
The passageway into the mound is roughly aligned with the summer solstice sunrise, shining on the back wall of the burial chamber for some weeks.
Bryn Celli Ddu is surrounded by Neolithic and Bronze age features, cairns and standing stones litter the area.