Brú na Bóinne. An area of continual human settlement going back to the Neolithic era found is found in the east of Ireland (County Meath), at the bend of the River Boyne. Here you will find buildings made so long ago that they pre-date the Pyramids of Egypt. Now that is old. I need to get myself here on my next visit to the Emerald Isle. And being only about 40 km / 25 miles north of Dublin makes it quite accessible.
In this UNESCO World Heritage Site (since 1993) you will find the three passage tombs of Knowth, Newgrange and Dowth (filled with Megalithic artwork) along with numerous monuments that show the ingenuity and skill of the ancient architects of that time. The incredible area is the largest of its kind in Europe at a size of 780 ha / 1,927 acres. The monuments range from those of social, commerce and funerary design. It has been determined that the passage tombs were constructed around 3,300 BCE through to 2,900 BCE with extensive consideration of solar and equinox alignment. It appears the architects knew what they were doing. Visiting this ancient part of Ireland is possible though only via guided tours and tickets are required.