President George Bush and his successor, Barack Obama, joined all the living US presidents for a historic meeting at the White House two weeks before the country's next transfer of power.
Bush, a Republican, and Obama, a Democrat, met privately for about 30 minutes ahead of the wider gathering and were expected to discuss the US economy and the crisis in the Middle East.
Then former Presidents Jimmy Carter and Bill Clinton, both Democrats, and Republican George H.W. Bush, the current president's father, met Bush and Obama in the Oval Office for a photo session with journalists.
"I want to thank the president-elect for joining the ex-presidents for lunch," the younger Bush told Obama, who stood next to him, nodding.
"One message that I have and I think we all share is that we want you to succeed. Whether we're Democrat or Republican, we care deeply about this country," Bush continued.
The five men, all standing in a line in front of the president's desk, smiled and rubbed shoulders, with Carter standing somewhat more to the side of the group.
The senior Bush stood next to Obama, with the current president next, followed by Clinton and Carter.
"All of us who have served in this office understand that the office itself transcends the individual and we wish you all the very best, and so does the country," Bush said to his successor. "To the extent we can, we look forward to sharing our experiences with you."
Obama called the gathering extraordinary and thanked the current president for hosting it.
"All the gentlemen here understand both the pressures and possibilities of this office, and for me to have the opportunity to get advice, good counsel and fellowship with these individuals is extraordinary," he said.
When asked by a reporter what he learned from the other four men's mistakes, Obama retorted: "From their successes!"
Despite last year's heated political campaign when Obama attacked Bush regularly over foreign and domestic policy, the transition process between the November 4 election and Obama's January 20 inauguration has proceeded smoothly.
Though they have much in common, relations between the different presidents have not always been rosy.
Carter has criticized Bush's presidency as "the worst in history" with regard to international relationships and Clinton, who has a warm relationship with the senior Bush, criticiced the current president and Obama sharply during his wife Hillary Clinton's White House bid last year.
Wednesday's event was the first such gathering of former US heads of state at the White House in 27 years. After their meeting in the Oval Office, the five men were to have lunch in a chandeliered private dining room.