The Winter Solstice at Newgrange in Co Meath can now be enjoyed by people all over the world as it is being streamed live online.
Weather permitting, it is hoped the live stream, organised by Fáílte Ireland, will capture the moment when the 5,000-year-old tomb's internal chamber is lit up.
The phenomenon occurs if skies are clear at dawn on the shortest days of the year from 18-23 December.
Light from the rising sun aligns perfectly with the 'roof-box' opening of the neolithic passage tomb, then travels up the 19-metre corridor, and enters the central chamber where it illuminates it completely.
The live stream event, which will begin at 8.30am, marks a special anniversary.
It was 50 years ago, on 21 December 1967, that Irish archaeologist Dr Michael J O'Kelly first documented the monument's solar alignment.
Access to the tomb is strictly limited each year on 21 December to a small number of people selected in a lottery system run by the Office of Public Works.
There were 32,522 entries for Solstice 2017.
The Winter Solstice traditionally marks the end of winter and the start of new life.