The tributes have been pouring in as the world marks the passing of Mikhail Gorbachev, who died last night at 91. A titan of the 20th century, he was the last leader of the Soviet Union, who raised the Iron Curtain and – along with his American partner President Ronald Reagan – ended the Cold War. Ten years after the fall of the Berlin Wall, Christiane spoke with President Gorbachev about the dissolution of the Soviet Union and his reflections a decade on. They had another, very different conversation in 2012, just after Vladimir Putin's re-election, during which he expressed worries about the authoritarian tendencies taking shape in Russia.  Also on today's show: Nina Khrushcheva, historian and great-granddaughter of Nikita Khrushchev, who put up the Berlin Wall in 1961; former US Ambassador to Russia Thomas Pickering; Adam Entous on his New Yorker piece, The Untold History of the Biden Family. To learn more about how CNN protects listener privacy, visit cnn.com/privacy Learn more about your ad choices. Visit podcastchoices.com/adchoices