Because of a trip I took to Ireland in 2001, I am the grateful recipient of a beautiful bi-monthly publication called "Ireland of the Welcomes".
In the most recent issue there is a long article about Newgrange, Knowth, and Dowth -- three 5000 year old stone age burial sites north of Dublin. Apparently, Newgrange is also an astronomical site, built in the stone age to mark the shortest day of the year.
Newgrange has a slit in the ground that focuses a sunbeam on the day of the winter solstice against the back wall of this long tunnel. Dec. 21 or 22 is the only day of the year when the sun can penetrate the tunnel and fall on the wall at the end.
These burial mounds are quite elaborate and decorated with many spirals and other figures of ornamentation. They were built by stone age people long before the pyramids of Egypt without the help of metal tools.
The article was fascinating, and I am sorry that Newgrange was not on our tour.
Saw them all in 2002. The elderly woman guide at Newgrange ranted on about how "grange" just meant farm and how the English were monsters, and unimaginative too, for calling it "Newgrange" meaning "Newfarm" instread of calling it by the name the Celts used.
Because my wife had made me promise to be on my best behavior I (barely) overcame my desire to speak up and point out that what ever the English or Celts called it, we don't know what the people who built Newgrange called it, because the Celts (with whom the present Irish in the Republic identify, especially when they accuse the English of cultutal genocide), had destroyed the builder's culture so throughly that we don't even know what the pre-Celtic inhabitants of Ireland called the monuments they built, including Newgrange.