millions watched him emerge karen allen has had rare access to the prison where he spent those final months. >> this is the villa in the prison where he spent his last year in custody. you can see that even haa swimming pool in the shadow of the mountains. by the time he reached here, it was clear that he was being prepared for bigger things on the outside. >> extraordinary to think that 20 years ago this was the nerve center of an attempt to liberate nelson mandela from prison. senior figures included bbc.co [unintelligible] in the last weeks of his incarceration he was secretly driven to cape town to hold talks to negotiate the terms of his release. >> on the 11th of february, 1990, nelson mandela was set free. he is now preparing to reflect on his past. his ex-wife has recreated the historic walk through the gates, joined by some of the heavyweights. 20,000 people are expected to mark this anniversary, knowing that despite the coming of democracy and the end of white minority rule, so of his ideas are work in progress yet to be realized. >> karen allen, thank you. we know that we