WASHINGTON-On a choice spot overlooking Washington's most stately monuments, a new museum swathed in bronze will showcase the tragedy and triumph of black America.

The National Museum of African American History and Culture, 100 years in the making and now almost ready, will fill a gaping void: until now the city had no grand-scale museum dedicated solely to this chapter of US history.

Slave cabins, a blacks-only train car from the segregation era and exhibits on the Reverend Martin Luther King and the civil rights movement he led will fill its halls, on the National Mall just a stone's throw from the White House and the Washington Monument.

So will a trumpet played by Louis Armstrong, training headgear worn by Muhammed Ali and a red Cadillac driven by Chuck Berry.

The museum opens on September 24 and Barack Obama, America's first black president, will cut the ribbon, in what promises to be a uniquely powerful, emotional moment.

The idea of building such a museum goes back to 1915. One of the inaugural exhibits, on the museum itself, is entitled "A Century in the Making."

"Often America is celebrated as a place that forgets," the museum's website says. "This museum seeks to help all Americans remember, and by remembering, this institution will stimulate a dialogue about race and help to foster a spirit of reconciliation and healing."

After years of false starts, a law calling for construction of the museum was passed in 2003 and signed by then president George W. Bush. Construction of the $540 million project began in 2012.

From the outside, the building features three distinct horizontal sections, their bronze-covered facades jutting out at a slight angle.

After entering, visitors are encouraged to go downstairs to see an exhibit on the global slave trade.

Right away, they run into a wooden slave cabin typical of the 1800s. This one was brought from a plantation in South Carolina and meticulously restored, board by board.

A series of ramps takes visitors through other periods of the black experience, such as segregation and the civil rights movement.

Artifacts on view along the way include a guard tower from a Louisiana prison built on land that was once a plantation that used slaves, and an airplane flown by the Tuskegee Airmen -- a celebrated company of black aviators who fought in World War II.

For all of its focus on some of this nation's most troubled episodes, the African America History Museum does not aim to be a criticism of America's past.

As visitors tour the cavernous museum possessing more than 34,000 artifacts, "what we see here, is the beginning of the culture that we have all built together," said Ralph Appelbaum, one of the architects who worked on the project.

"As you go on, you see more and more symbols of that integration, of freedom," he told AFP while standing under the Tuskegee aircraft, suspended from one of the ramps.

The museum's location -- the last available spot on the Mall for such an expansive edifice -- is commensurate with its importance, said another architect, David Adjaye.

The upper floors of the museum are dedicated to sports, music, entertainment, food and pop culture, with things like the fist-bump.

"I see that as a celebration of the contribution of African Americans to US culture," said Joanne Hyppolite, a curator.

At the end of the tour on the top floor one can view Chuck Berry's Cadillac and memorabilia from the Jackson Five pop music group of the 1970s.

Still-empty glass cases are marked with names like Michael Jackson, Duke Ellington, Ray Charles, Prince and Ella Fitzgerald.

The top floor, offering a spectacular view of some of the 18 other Smithsonian museums -- is meant to be a place of contemplation.

Along the way, visitors already had a chance to read old reflections, such as wall writings with the words of one Felix Haywood, son of a slave, musing on the moment of emancipation in the 19th century. "We was free," Haywood reminisced. "Just like that, we was free."