Volkswacht Bodensee - Ex-presidents and stars, but no Trump, turn out for Obama Library

Obama, 64, struck his trademark hopeful tone in a speech inaugurating the modernistic center.

The country's first Black president alluded to fears among many Americans that US democracy is in danger, winning applause with the phrase "no kings" -- a popular anti-Trump protest slogan.

But Obama also said that an "overwhelming majority" wants the nation to heal.

"People aren't looking for perpetual anger and division," he said. "They are looking for fairness and common sense and mutual respect."

The futuristic complex housing Obama's records and mementos from his two terms in office opens to the public on Friday.

Thursday was for celebrities including Steven Spielberg, Tom Hanks and Oprah Winfrey, alongside performances by U2's Bono, Stevie Wonder, Bruce Springsteen and hip-hop band The Roots.

This was also one of those rare occasions when the country's former presidents gathered in one place.

Republican George W. Bush and Democrats Bill Clinton and Joe Biden walked on stage, joining Obama, his wife Michelle Obama and their daughters Sasha and Malia.

Not only was 80-year-old Trump absent but he routinely continues to launch criticism and often personal insults at Obama, shattering the informal truce traditionally observed within the presidents' club.

"I'm so disappointed we've reached this point," Illinois Senator Dick Durbin said of the acrimonious environment in Washington.

"I'm honored that President Bush would make this a bipartisan salute to Barack Obama and Michelle," he added. "We need to get back in that spirit again, and we can, America can get through this and come together."

Foreign guests at the gathering included former Italian prime minister Matteo Renzi and former German chancellor Angela Merkel.

Meanwhile, hundreds of Chicagoans watched from a distance on the Midway Plaisance, the mile-long park stretching past the University of Chicago, where Obama once taught law.

- Chicago, launchpad for Obama -

Chicago's South Side played a prominent role in Obama's career.

He cut his political teeth there as a community organizer in the 1980s before representing the area in the Illinois state Senate, then winning a US Senate seat in 2004.

Still in his first term as a senator, he launched an outsider bid for the presidency and went on to win two terms, leading the nation between 2009 and 2017.

Now the neighborhood will play host to the former president's complex, which features an NBA-sized basketball court -- a nod to Obama's and Chicago's shared love of the sport -- and the 225-foot (69-meter) tall granite tower housing his museum.

The stark architecture has drawn astonishment and outright criticism, with Trump comparing it to a trash can. More generous critics have called the building the "Obamalisk" and compared it to a "Star Wars" spaceship.

But the $850 million center will enshrine Obama's core message of "hope," said Valerie Jarrett, CEO of the Obama Foundation and a former top White House aide during his presidency.

There is a sprawling playground and a public library. But unlike the other 15 official US presidential libraries around the country, it will store archives digitally instead of having physical copies.

"Chicago has produced so many things," said Illinois Congressman Danny Davis, who has represented Chicago’s West Side since 1997.

"It's been a centerpiece of the Civil Rights movement, of human rights, of social work, of social development, of social activity and of course, in terms of race relations and race development, the only place from which an African American has become president of the United States."

F.Wagner--VB