Take a dazzling architectural journey inside those majestic marvels of Gothic architecture, the great cathedrals of Chartres, Beauvais and other European cities. Carved from 100 million pounds of stone, some cathedrals now teeter on the brink of catastrophic collapse. To save them, a team of engineers, architects, art historians, and computer scientists searches the naves, bays, and bell-towers for clues. NOVA investigates the architectural secrets that the cathedral builders used to erect their towering, glass-filled walls and reveals the hidden formulas drawn from the Bible that drove medieval builders ever upward.