17. Six Millenia
The area surrounding the site known as the Boyne region has also been a huge hub of human activity for the past six millennia. The burial grounds on the area date back as far as 5,000 years ago. The most ancient structure in the area actually dates back farther than the Pyramids of Giza. However, the most amazing part of all of this is that due to the nature of the construction of these sites, it is obvious that the builders had a knowledge of science and astronomy.