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.

[2] The mound, being substantially smaller than as originally made, no longer completely encloses the burial chamber, so the back wall is open to the air, allowing some natural light in.

[3] Free-standing inside the burial chamber is a smooth pillar of blueschist,[4][5] a metamorphic rock, some 2 m (6.6 ft) high, with a very rounded shape.

Two further cairns have been identified just to the south of Bryn Celli Ddu,[8] while in the field immediately to the west is a standing stone,[9] and a rock outcrop with cupmarks carved into it.

Individual human bones, both burnt and unburnt, were found within the chamber and passage, suggesting a variety of funeral practices, but in all cases re-using the tomb, and clearing aside the old remains.

In 1802 Rev John Skinner made a "Ten Days' Tour Through the Isle of Anglesea", an account of which he wrote up, but never published, describing the numerous archaeological sites he visited.

[13] It has since been moved to the National Museum of Wales and replaced with a replica standing outside the back wall, but within the area of the original mound, and close to the spot where it was found.

[3] The Pillar was set back upright, and the earth and stone mound covering the passage and chamber was reinstated, but clearly there was much less material available than had been used originally.

[3] Norman Lockyer, who in 1906 published the first systematic study of megalithic astronomy, had argued that Bryn Celli Ddu marked the summer solstice.

Steve Burrow, curator of Neolithic archaeology at Amgueddfa Cymru (National Museum of Wales), has more recently supported the case for summer solstice alignment.

This alignment links Bryn Celli Ddu to a handful of other sites, including Maes Howe, Orkney and Newgrange, Ireland, both of which point to the winter solstice.

[16] The serpentine pattern and the passage tomb featured strongly in the short animated film, Songs from Stones, about some of Anglesey's evocative archaeological sites and artefacts, produced as part of the Cultural Olympiad in 2012.