This ancient site in southeastern Ireland is just over 5,200 years old ... They are thought to be man-made Megalithic "passage tombs," thought of as underground grave sites resembling large ...

The remains of 1,000 massive stone burial sites, mainly from the Neolithic period, are scattered across Ireland ... transported and manufactured the megaliths is still a mystery that connects ...

In the Boyne Valley in Ireland, the Newgrange monument has stood ... The building materials sometimes came from distant sites ...