Matt Frei is the BBC's Washington correspondent. Born in Germany, he was sent by the BBC to Berlin in 1989 to report on the fall of the Wall. Now, 20 years later, he returns to take us on a fascinating journey through Berlin's history to reveal the true spirit of the city. Over three hour-long documentaries he explains this incredible city's ideas, building and people. Dangerous Ideas explores how Berlin has been a crucible for radical thought – giving birth to communism and fascism, theories of sex and sexuality, eugenics and the atomic bomb – and how the price of such experimentation has been a history of bloodshed, tyranny and violence. Ruined Visions tells a story of human creativity and destruction through the buildings of Berlin. From Friedrich the Second's Imperial city and Bauhaus to the impact of Speer's Neo-classical Nazi dream and the Wall; what began as a 17th century provincial town became a city unique in the world. Ich Bin Ein Berliner (I am a Berliner) reveals the spirit of Berlin's people, characterised by their struggle for freedom. Having flocked to enjoy the city's religious toleration, they took on the Nazis and risked their lives to cross the Wall – the iron rod of oppression and a thirst for liberty have shaped the Berliner.