In what is described as the fitting coda to his administration, President Obama will cut the ribbon of the Smithsonian’s new National Museum of African American History and Culture on 24 September. Journalists Jesse J Holland and Robin N Hamilton are onsite in Washington DC for BBC World Service to hear from the architects, curators, donors, and expectant visitors who have travelled hundreds of miles to celebrate its grand opening. Taking the last spot on America’s National Mall, the museum – a beautiful three-tiered structure sheathed in bronze metalwork - will open after what’s described as the hardest curatorial job in history. It has been more than ten years in the making. It’s a museum that will explain, celebrate and confront the African American experience. At a time of racial tension, its mission to heal is seen as vital too. Museum director Lonnie Bunch, congressman John Lewis and judge Robert Wilkins describe the challenges of creating a museum which aims to tell the story of America through the lens of the African American experience. A story which is bound to provoke distress and anger as well as joy and admiration - something the museum’s 250 volunteers are being specially trained to deal with. We hear from two founding donors, Samuel L Jackson and General Colin Powell about the importance of having a national museum dedicated to African American history and culture. From locations across the USA - Philadelphia, Detroit, Houston, St Louis, Nashville - we uncover stories behind the museum’s varied new acquisitions, largely told by the donors themselves: from Harriet Tubman’s Hymn book to Lauren Anderson’s ballet shoes, protest banners from Ferguson, the late music producer J Dilla’s synthesizer, and a former slave’s printing press. And we follow inspirational young divers in South Florida working in partnership with the museum to locate long-lost slave wrecks.