Known anciently as Brugh na Boinne “Place of the Boyne” Newgrange is said to be the tomb of ‘three times fifty sons of kings’ belonging to the legendary kingdom of Tara (Illustrated guide to Newgrange by O’Kelly) It is also identified as the sidhe of Angus Mac Og, leader of the Tuatha da Danann- the children of the godess Danu/ Dana.
One legend “The Dream of Angus” relates how he fell in love with a swan-maiden after she visited him in a dream. After she agreed to marry him, they fly off to Newgrange in the form of swans, where they lived happily ever after. In Scottish folklore, Angus was married to the goddess Bride, who was herself a swan-maiden.
This is an interesting refernce as Newgrange itself may represent the layout of the constellation Cygnus- The Swan.