These perfectly round holes in the wood are not man-made but are the result of larvae of the wood wasp or horntail biting their way into freedom after years of living inside the tree.
In contrast, this circle is entirely man-made. As are the curvy reflections in the window.
The Berlin TV tower built in the 1960s on the East German side.
And last not least these spheres of light on a curve for Cee’s black and white challenge: circles and curves.