It is impossible to weigh which single Gothic building has the most beautiful stained glass artwork. Stained glass is a crucial element in Gothic architecture, as imagery in stained glass helped illustrated Bible stories to a population that cannot read or write. Due to advances in glassmaking in the 12th century, glassmakers were able to construct larger, more ornate pieces. As Gothic architecture made buildings stronger that enabled larger windows, stained glass pieces can be made bigger and more beautiful. The most popular example, still with majority of original stained glass windows intact, would probably be the Chartres Cathedral.