Can architecture inspire people to change the way they think and behave? Sarah Montague speaks to architect David Adjaye, who has designed buildings including the Nobel Peace Centre in Oslo, a business school in Moscow, shopping centres in Beirut and Lagos, a children's hospital in Rwanda, and a housing project in New York's Harlem. Adjaye's biggest project yet is about to open - the National Museum of African American History and Culture, located on the National Mall in Washington DC. Has he got the design right? What is the test of a good building?