In summer 1814, a four-metre parchment was discovered in the attic of a Darmstadt inn. The court architect Georg Moller identified it as the left half of a medieval plan of Cologne Cathedral’s facade. He informed Boisserée, who viewed it together with Goethe. In 1815, Moller and Boisserée discovered the right half of the plan in Paris. It showed the southern tower with the middle section of the building, and made it possible to construct the western facade in accordance with the medieval plans.