Bryn Celi Ddu was a large circular cairn of stones covering a passage 27 feet (over 8 metres) long, leading to a central, polygonal chamber. This had a small spiral carved into one upright, visible only by artificial light, while a megalith with an elaborate serpentine design was put face- down over a pit in the centre of the site before the monument was constructed over it. The passage points at the midsummer sunrise, which lights up a quartz- rich monolith at the back of the chamber.
The developed passage grave of Bryn Celli Ddu was apparently built over a henge monument containing a stone circle, which was destroyed to make way for it, the stones being removed, broken or toppled.
from Pagan Britain; Ronald Hutton
Music: The Host of Seraphim, which is the opening track from the 1988 album The Serpent's Egg by Dead Can Dance. Of the album, AllMusic wrote, "Perry and Gerrard continued to experiment and improve with The Serpent's Egg, [in particular]… The Host of Seraphim [is] "so jaw-droppingly good that almost the only reaction is sheer awe."