Munich-style stained glass was produced in the Royal Bavarian Stained Glass Manufactory, Munich, in the mid-19th century. King Ludwig I, opened the glassworks in 1827 which continued production of high quality glass until the early 20th century. Franz Xavier Zettler headed the operation for much of this time. Together with his major competitor, Franz Mayer of the Royal Art Institute, these stained-glass artists developed the so-called "Munich style" of expert painting on relatively large glass panels (as opposed to the medieval technique of smaller pieces of colored glass held in a leaded framework, later adapted and modified by the great American designer Louis Comfort Tiffany).