Images of flames devouring the Notre-Dame cathedral in Paris on April 15, 2019 shocked the world. A detailed two-part documentary featuring video and 3-D animation unveils some of the secrets of the famous church. The film looks back on how, with courage and ingenuity, the structure's creators and craftsmen developed a new style that changed ecclesiastical architecture in France and Europe. Built between 1163 and 1345, the cathedral was one of the first Gothic churches in medieval France. The documentary focuses on the master builders - their vision, the risks they faced, project setbacks and successes - while blending in genuine video material that sheds light on historical and technical details. It examines the famed rose window and how it was created, as well as the cathedral's iconic gargoyles. Victor Hugo's novel "The Hunchback of Notre Dame" was published in 1831, giving the church a place in world literature. The two-part documentary pays homage to the world-famous, much-loved cathedral.