With apologies to 1990s alt-rock fans, a perfect circle cannot exist outside the realm of mathematics. From subatomic particles to carefully built structures, nothing in the physical world passes the perfect circle test, where every point on the circumference is exactly equidistant from the circle’s center. That said, some notable natural forms and human-made buildings get pretty close. Occurring either by happenstance or designed to pay homage to the shape that the Greek scholar Proclus called “the first, simplest and most perfect form,” these sites highlight the singular symmetry and symbolism the circle embodies.
A fascination and interest in circles predates recorded history, with many ancient cultures finding approximations for pi—the ratio of a circle’s circumference to its diameter—thousands of years before mathematicians gave it that name with the tasty homophone.
Because of their symmetry, circles were seen as representations of the “divine” and “natural balance” in ancient Greece. Later on, the shape would become a vital foundation for the wheel and other simple machines.