The Gothic cathedrals are marvellous human achievements in architecture and artistry. Building the Great Cathedrals investigates how medieval architects could conceive and construct grand religious buildings such as the Beauvais Cathedral of France. It explores the logistics of acquiring the stone and other materials used in the construction of a cathedral, discusses how such an endeavour could require the manpower of entire towns and how the construction of some sites transitioned from one living architect to the next.
The documentary then transitions into a discussion of how many of these great works are in decline, if not ruination. It highlights the joint efforts of international groups of artisans, architects, engineers and other learned professions in the pursuit of preserving and restoring the cathedrals, as well as informing the audience about the specific techniques used to construct these buildings in the first place. The film also serves as an introduction to the vocabulary of religious architecture.