Worms has been a Roman Catholic bishopric since at least 614, and was an important palatinate of Charlemagne. Worms Cathedral is one of the Imperial Cathedrals and among the finest examples of Romanesque architecture in Germany. Worms prospered in the High Middle Ages as an Imperial Free City. Among more than a hundred Imperial Diets held at Worms, the Diet of 1521 (commonly known as "the" Diet of Worms) ended with the Edict of Worms in which Martin Luther was declared a heretic. Today, the city is an industrial centre and is famed as the origin of "Liebfraumilch" wine. Other industries include chemicals, metal goods and fodder.