James Brechney traveled from Australia to chalk a rainbow with interns and employees at Facebook's headquarters to celebrate Gay Pride Day on June 27.
A barbecue equipment salesman from Australia, Mr. Brechney drew rainbows in the backyard of his house in Australia last year after government workers erased one sketched on the street.
After a photo of his redecorated house went viral on Facebook, people worldwide started chalking rainbows.
"To chalk around my house was sort of a joke. And a year later to be here at Facebook headquarters is a dream," he said. "This campaign is a conversation starter. It's so innocent and beautiful.
"It creates amazing awareness. We get a lot of emails and letters from kids at school, who get bullied. They just love seeing all the photos coming in from all over the world."