Almost 2,000 young people from around the world have converged on Belfast for a conference billed as bringing together the global leaders of tomorrow.
Delegates have come from 190 countries to the city for a four-day forum called the One Young World summit.
The opening ceremony took place tonight, with formal events happening in the coming days.
Over the course of the four days, delegates will hear from speakers including Irish singer and campaigner Bob Geldof.
During the week the young people will take part in workshops and be mentored by influential political, business and humanitarian leaders.
Northern Ireland born Oscar winner James Martin also addressed the opening ceremony.
He said he was proud to stand on the One Young World stage in Belfast: "To win an Oscar, I hope it has given hope to everyone and other people with down's syndrome and other learning difficulties and those with autism, cerebral palsy and other conditions.
As an example, one young girl wrote to me and said 'I was watching the Oscars with my family and you came up to get your award, and I said to them oh look … he looks just like me’. As I say always, never judge a book by its cover."
Later in the week there will be a session looking at the legacy of the Good Friday Agreement and potential lessons for other countries caught in conflict.
Former Taoiseach Bertie Ahern and former President Mary Robinson will participate over the course of the week.
Former Manchester United defender Rio Ferdinand and Nazanin Zaghari-Ratcliffe, an Iranian-British citizen who was released in 2022 after six years in an Iranian prison, will also speak.
Themes on the agenda for discussion include education, climate change, food shortages, mental health, and peace and reconciliation.
As part of the summit, One Young World will present an inaugural journalism prize, the Lyra McKee Award for Bravery, in honour of the journalist who was shot dead by the dissident republican group the New IRA while observing rioting in Derry in April 2019.
Belfast Lord Mayor Ryan Murphy said the city is looking forward to "bringing exceptional young leaders, activists and business leaders from every corner of the world together to find solutions to the important issues facing our world today."