Max Pearson presents a collection of the week's Witness History episodes.

We hear the story of the largest unfinished Catholic church in the world and the creation of one of the most recognisable characters on the planet.

Plus, an amazing first hand account of the expulsion of German-speakers from Czechoslovakia at the end of the Second World War, the man behind Dignitas, the assisted dying organisation in Switzerland, and the son of a Guatemalan president who was overthrown in an American-backed coup in the 1950s.

Contributors:Mark Burry - architect, who was part of a team trying to piece together Gaudí's vision for the Sagrada Família.Madeleine Kessler - architect from Madeleine Kessler Architecture.Yuko Shimizu - the artist who designed Hello Kitty.Helmut Scholz - a Sudeten German, who was expelled from Czechoslovakia after the Second World War.Ludwig Minelli - the lawyer behind Dignitas, the assisted dying organisation.Juan Jacobo - the son of the former Guatemalan president Jacobo Árbenz.

(Photo: The Sagrada Família, in Barcelona. Credit: Getty Images)