The largest artwork in history, with over 1,000 circles created by sand artist Jim Denevan, in Nevada, USA, 2009. Nine miles in circumference across the desert setting. Awesome achievement - larger than the lines in Nazca, Peru. The design is based on a mathematical theorem called an Apollonian Gasket and features triples of circles at tangents to others. Jim is also the founder and organizer of a worldwide moveable feast called Outstanding in the Field. His main site is here.
