York Minster is famous for having the greatest concentration of medieval stained glass in England.
The minster preserves a remarkable sequence of windows dating from the 12th through the 15th centuries. They represent several stages of English Gothic design, from early grisaille and narrative panels to enormous later compositions such as the Great East Window.
York’s survival is especially significant because many medieval windows elsewhere were damaged or destroyed during religious changes, warfare, iconoclasm, and later renovations. The minster’s glass also records the importance of guilds, wealthy families, clergy, and monarchs as medieval patrons.
The phrase refers to the concentration and range of surviving medieval glass, not to a claim that every panel is intact or that York has the world’s largest total area. The Minster’s medieval windows are now protected through extensive conservation work.