The outside is impressive enough, with its re-constructed stone facade, but it is the opportunity to go inside the mound that makes this one of the can't miss sights of Ireland. Imagine a dry stone construction so exact that it has remained watertight for over 5,000 years, and still admits sunlight only on the morning of the winter solstice. If you can, go first thing in the morning so that your tour will not be too crowded. Also, while you are there, take the tour to Knowth as well. While not as awe-inspiring (largely because of the lack of interior access) there are several things you can see at Knowth that you cannot see at Newgrange. However, if you have time for only one of the two, it must be Newgrange.
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