Sardinia, Su Nuraghe, The arch of Barumini
http://slicer93.mbsrv.net/20130126235845.jpg
The reason why I went to Sardinia was I had wanted to know the meaning of this arch.
Though I had not known the reason until today but I found it now.
This stone tool like a basin rotated , gathered the atoms and made the figure of Stone humans or humans.
Atoms were bonded more firmly by passing through the arch.