Marina and Ulay began collaborating as artists and lovers in 1976. When they felt the relationship was reaching its end in 1988, they decided to walk the Great Wall of China, each from one end, to meet in the middle and then never see each other again. Here they are, meeting once again in a 2010 performance at the MOMA, where Marina sat in a chair and invited strangers to sit opposite her and look into her eyes.