Newgrange

Newgrange was constructed over 5,000 years ago (about 3,200 B.C.), making it older than Stonehenge in England and the Great Pyramid of Giza in Egypt. Newgrange was built during the Neolithic or New Stone Age by a farming community that prospered on the rich lands of the Boyne Valley. Knowth and Dowth are similar mounds that together with Newgrange have been designated a World Heritage Site by UNESCO  Click to read more....   

Sources:  
The Knowth   
Mythical Ireland   
Newgrange Ireland
Meath.ie  
World Heritage Ireland   
Megalithic Ireland  
Voices from the Dawn