In Ireland there are passage tombs that are 5000 years old, according to C14 tests. Most of them have carvings on different places: the passage, the main chamber, the exterior... and not in a consistent way. I guess that many of them were lost because of wind and rain.

There are two main places in Ireland, Newgrange and Loughcrew (there are videos on youtube and websites with pictures). These tombs have solar alinements and their ultimate use is unknown, althoug the main guess is that they were tombs. The carvings have circles, waves, stars... all very basic forms.

What was the meaning of those carvings? what was the use of those constructions? some stones weight 10 tns and they had no wheels at that time.