The Winter Solstice takes place this morning.
Hundreds of visitors are expected to make the pilgrimage to Newgrange in Co. Meath, to see the sun illuminate the inner passage of the tomb.
Only a limited number of people are allowed inside the neolithic chamber to witness the event this morning.
Leontia Lenehan, Supervisor Guide at Brú na Bóinne, says a lucky lottery winner from home and abroad will be going into the chamber.