Newgrange - pile of stones of some interest. Tomb conveniently doubling as a calendar; time marker, seasonal whatever... Was used for quite a while (a couple hundred years or so) before it was abandoned and cheaper calendars came out (no really - there are smaller standing stones in front that were probably usable all year around as opposed to once.) The mound was built before the wheel and metal, about 500 years before the pyramids in Egypt, by people that had the wealth to do it.
Check it out - marvel at the ability of 19th century archeologists to reconstruct what they thought was right.
Entrance stone. One of three with similar decorations around the circumference of the mound. The guide made much of these - basically along the lines of "We have no clue, make up your own mind what the carvings mean."
The interior is amazing considering it's over 5000 years old. (No photography allowed)
The tunnel leading in lines up with the position of the sun on December 21 (winter solstice ). The guide gave us a little preview of how it would look. She turned off the lights so everything was pitch black and as quiet as, well, a tomb, which was quite a feat considering there were around 20 people inside. She turned on a light positioned at the sun's position and a ray coursed its way through to our location inside and lit up the room, illuminating all the carvings and the gorgeous corbeled ceiling.
This was right behind Newgrange it looks "modern".