Le Corbusier was arguably the 20th century's greatest architect; an idealist whose "white cube" houses and visionary writings brought him worldwide acclaim. Yet as he grew older, he claimed a connection with the Cathars, a persecuted 13th-century sect. Why would a renowned modernist, an atheist from a Protestant background, insist on an affinity with medieval Catholic heretics?
Jonathan Glancey explores Corbusier's possible reasons and considers the effect this spiritual bond had on his life and work. Producer Rebecca Nicholson