Reference
Overview:
The most famous challenge in classical Greek mathematics is the problem of squaring the circle or "quadrature" - To construct geometrically a square equal in area to that of a given circle. The expression ‘circle squarer’ has been applied to those who attempt the impossible. Aside from the Greeks the Chinese, Arabs, and Europeans have been fascinated with this problem for thousands of years. more info


  "Vitruvian Man" a Fine Example ?
"Throughout his life, Leonardo sought solutions to the problem of squaring the circle"... "Although the text on the drawing makes no specific mention of squaring the circle, the question nevertheless arises... more info (Leonardo2002©)


Reference Links:
The following should help to gain an understanding of "the squaring of a circle" and :

Leonardo De Vinci's Vitruvian Man

Squaring the Circle is No Piece of Pi

Circle Squaring Eastern Philosophy

More on the Vitruvian Man