Kaleidoscopic Floor Installations Made of Mirrors, Crystals and Glass by Suzan Drummen
Video showing what happens when you take a completely white living room, thousands of colourful circular stickers and lots of children. Yayoi Kusama’s legendary installation, Obliteration Room:
Crop circles - fabulous 'art' on a huge scale
.... some circles in architecture .....
....circles in the sand
Kandinsky loved painting circles:
and so did Delaunay (Thanks to @lennyvalentino for letting me know about him):
Jake Beckman sculpture made from cycle wheels: