The dynamite bomb went off outside the church Sept. 15, 1963. Of the Klansmen convicted years later, one remains imprisoned. Two others convicted died in prison.
Two young men, both black, were shot to death in Birmingham in the chaos that followed the bombing.
Birmingham was strictly segregated at the time of the bombing, which occurred as city schools were being racially integrated for the first time. The all-black 16th Street Baptist was a gathering spot for civil rights demonstrations for months before the blast.
The bombing became a powerful symbol of the depth of racial hatred in the South and helped build momentum for later laws, including the 1964 Civil Rights Act and the Voting Rights Act of 1965.
During the commemoration, an honor guard composed of black and whites officers and firefighters watched over ceremonies with mixed-race crowd, something unthinkable in Birmingham in 1963. That same year, white police officers and firefighters used dogs and water hoses on black demonstrators marching for equal rights.
Rev. Bernice King, a daughter of the late Rev. Martin Luther King Jr., noted the changed city in a prayer.
“We thank you father for the tremendous progress we have made in 50 years, that we can sit in the safe confines of this sanctuary being protected by the city of Birmingham when 50 years ago the city turned its eye and its ears away from us,” she said.