You may have heard of Carnac... no, not "Carnac the Magnificent" the Johnny Carson (I can hear many young people saying "Who?") character. This Carnac is in Brittany (France) and is, in many opinions, the most important megalithic site in the world, surpassing Stonehenge. It's comprised of thousands (as in over 3,000) prehistoric megaliths (from the Greek meaning "large stone") which were placed sometime between 3,300 and 4,500 B.C. Standing amidst the stones, placing your hand on them and looking at the vast field of perfectly placed menhirs (some up to 180 tons) is a truly unique experience.
We often are filled with arrogance, thinking that we're the smartest most advanced civilization since time began, and that those who came before us lived in ignorance...just seeing this and pondering how a society that lived some 7,000 years ago was advanced enough to conceptualize and create such a site, whatever its purpose (religious, astronomical, its purpose will remain a mystery) is humbling and inspiring.