More than 1,000 protesters took to shining lights on the sails of the Sydney Opera House to obscure a promotion for a racing event called The Everest.
They aimed their torches, flashlights and smartphones at the opera house in a bid to wash out a projection for the event.
The opera house has a policy in which logos, corporate identities or colors are forbidden from being projected onto its sails, as to not undermine its heritage status.
The projection has received backlash from the opera house's CEO Louise Herron, who spoke out against it. A petition with more than 300,000 signatures from members of the public supported Herron's stance, saying they were unhappy that the opera house was being used as a billboard for gambling.
However, Australian Prime Minister Scott Morrison defended the deal made by New South Wales' State Premier Gladys Berejiklian's with Racing NSW. He also called the opera house "the biggest billboard Sydney has."