I first saw Bernar Venet's mathematical sculpture quite a few years ago in Quebec City. It was his signature bundle of arcs like the ones I saw at Universitaet Mozarteum, Salzburg last year:
Then I discovered his very unique wall paintings in a mathematical journal when I was studying homological algebra at graduate school. I love the way he brought two of my favourite things, art and mathematics, together unpretentiously.
Image from http://www2.math.uni-paderborn.de/