Roman Opalka, a leading conceptual artist who, beginning with the numeral one in 1965, methodically painted numbers has passed away at 79.

Sarah Greenough leafed through 25,000 pieces of steamy letters exchanged by Georgia O'Keeffe and Alfred Stieglitz for her new book.

"Curtain Call" concept, consisting of 5,600 silicon rods hanging from an 18 meter diameter ring at Ron Arad's big screen debut.