based on a detail of Pantheon's dome
architectural masterpiece of the 2nd century ad.
the whole dome is 43,3m wide, still the biggest unenforced concrete dome in the world , even St. Peter's is 1,4m smaller, much to the dismay of the popes
the oculus in the middle alone is 9m wide
when staring up long enough, the concrete starts to move, the eye focusing on you....