JOHANNESBURG — Sello Hatang pulled open a long, yellow drawer and grabbed a cream-color parchment. It declared Nelson Mandela an honorary citizen of the State of Washington.

Underneath was a similar one from Wisconsin and, below that, a key to the City of Chicago. In the dozens of other drawers lining the room were similar documents from around the world, and above them shelves full of gifts from foreign dignitaries, crystal award statues and shiny bronze figurines.

This is ground zero in the effort to maintain and shape the legacy of Nelson Mandela — widely referred to here as Madiba, his clan name — and to make sure that the narrative of the struggle does not deviate too much from what Mr. Mandela wanted it to be. It was also the site chosen on Saturday for the meeting between President Obama and members of Mr. Mandela’s family.

“Everyone has an agenda, so we have an agenda, too,” Mr. Hatang, the chief executive of the nonprofit Nelson Mandela Center of Memory, said Friday afternoon. “But we want to be seen as trusted brokers. We want to keep the record accurate and to maintain Madiba’s papers and possessions in a place that both the public and scholars can access them and keep the historical record pure.”