The legendary band Queen and glam frontman Adam Lambert led a packed Central Park in mobilizing world governments to pledge international aid to eradicate extreme poverty and tackle climate change.
An estimated 60,000 people crowded the Manhattan green space for the Global Citizen Festival, an unofficial exclamation point to the United Nations General Assembly which distributes free tickets to people who have worked toward the greater social good.
Entertainment mogul Pharrell Williams, soulful pianist Alicia Keys, R&B prodigy H E R, pop band OneRepublic, K-pop boy band NCT 127 and singer-songwriter Carole King also played at the festival.
Now in its eighth year at New York's Central Park, the day of concerts saw fans young and old sway to classic Queen hits like We Are The Champions, Bohemian Rhapsody and We Will Rock You.
Lambert, who has toured with the band for eight years, led the charge as veteran Roger Taylor helmed the drums and guitarist Brian May delivered his signature guitar solos.
The flamboyant Lambert went through a series of dramatic costume changes, finishing the show wearing a crown and a bright red military-esque uniform, as May dropped his long trench coat to reveal a T-shirt featuring the image of Queen's original lead singer Freddie Mercury, who died in 1991.
Like many of the other performers, Lambert used the moment to urge environmental protection.
"We're asking fans to take action, to ask certain governments around the world to take part in helping take care of our oceans," Lambert said. "Fish and wildlife in the ocean are literally gagging on pieces of plastic and it's killing them."
A day before, the former American Idol contestant had said he was thrilled to take part.
"I love that they're encouraging people to push the more wealthy world governments into backing these initiatives with real funding so that the real change can happen," he said.
"They're getting people involved on a task level, so it's actually educating all of our audience members. It's a really brilliant set-up."
Hollywood A-lister Leonardo DiCaprio made a surprise appearance to praise youth activists, including the Swedish teenager Greta Thunberg, who have taken to the streets and addressed world leaders in leading a global climate movement.
"Millions of individuals did more than simply walk out of their schools and places of employment. They took a stand," DiCaprio said. "They set an example of true leadership that our planet so desperately needs. These young people have said clearly, definitively and without fear, that the time for inaction is over."
The Prime Minister of Antigua and Barbuda, Gaston Browne, unveiled a new path for the island nation to tackle plastic waste and design alternative materials, as Norway's Prime Minister Erna Solberg increased contributions to the Global Fund to Fight AIDS, Tuberculosis and Malaria to US$228 million (HK$1.8 billion) by 2023.
Germany pledged US$11.1 million to the "Education Cannot Wait" fund, aimed at assisting children living in conflict and crisis zones, as Switzerland vowed US$6 million to it.
Earlier this week, Global Citizen announced a year-long campaign pushing world governments to get "back on track" with the Global Goals for Sustainable Development.
The event will feature a Central Park concert along with one in Lagos, Nigeria, and cities in Latin America, Europe and Asia.
A list of artists including teenage star Billie Eilish, funk futurist Janelle Monae, R&B superstar Usher and heavy metal band Metallica have already pledged to perform.
"This really is the most important 10 years for the movement to eradicate extreme poverty and tackle climate change," said Hugh Evans, the founder and chief executive of Global Citizen.
During Keys' rousing performance that featured her own hits as well as a smashing duet with H E R of Aerosmith's Dream On, the New Yorker praised the crowd for its activism and encouraged future efforts.
"We believe in love," Keys said to cheers. "We believe in change. We believe in greatness."