What is the place that's famous for the Winter Solstice in Ireland?

You must be talking about Newgrange. For over 5,000 years, this megalithic monument has stood amidst one of the world's most important prehistoric landscapes, Brú na Bóinne (the Boyne Valley) in County Meath, which makes it older than both the Pyramids at Giza and the standing stones at Stonehenge. 

There's a bit of mystery surrounding its purpose - archaeologists classify it as a passage tomb, but it's widely recognised as having a much deeper significance for its Stone Age builders.

For millennia now, something remarkable happens between December 18 and December 23; for 17 magical minutes, a single beam of light from the rising sun penetrates the small opening over the entrance. It creeps slowly along the narrow stone passageway until it reaches the burial chamber at the centre of the structure and bathes it in a golden glow. 

So how often do you get to see this wondrous spectacle? Access is decided by lottery so you can throw your name into the metaphorical hat, and who knows - you might be one of the lucky ones. Just remember - the experience is weather-dependent, but even if it's cloudy, it's a pretty special experience. 

If your name isn't hand-picked, don't worry. Spectators are welcome to come and stand outside the monument to soak up the atmosphere. And if you can't make it during the Winter Solstice, you can still see a simulation of the lightshow at any time of the year when you visit Newgrange.

Access is strictly through the Brú na Bóinne Visitor Centre, where you'll get a great overview of this extraordinary landscape. As well as Newgrange, you can visit Knowth, Brú na Bóinne's largest passage tomb, and discover more about the ancient and highly-skilled society that built it.

While you're here in Ireland's Ancient East, you can also check out Loughcrew in County Westmeath - another Stone Age marvel that boasts a similar lightshow during the Spring and Autumn solstices.

Check out this link https://www.marblearchcavesgeopark.com/geopark-events/ - the Cavan Burren Forest Park is the most magical of places to experience the Winter Solstice.  

I suspect, weather permitting, there would be no more atmospheric place to view the Winter Solstice than from the walls of the great hill-top fortification of Grianan of Aileach in Inishowen, County Donegal, near Derry city, with commanding views over Loughs Foyle and Swilly and the counties of Donegal, Derry and Tyrone.

Grianan of Aileach, with its panoramic views over the surrounding countryside, was built here as a symbol of royal power. This large stone-walled fort was the royal citadel of the northern Ui Neill from the 5th to the 12th century. Three earthen banks circle the Grianan which may be part of an earlier Bronze Age or Iron Age hillfort.

The Navan Centre & Fort, Armagh are also planning a Winter Solstice event https://visitarmagh.com/whatson/winter-solstice/