Stained glass windows of Chartres Cathedral
The stained glass windows of Chartres Cathedral are held to be one of the best-preserved and most complete set of medieval stained glass, notably celebrated for their colours, especially their cobalt blue. They cover 2600 square metres in total and consist of 167 windows illustrating biblical scenes, the lives of the saints and scenes from the life of trade guilds of the period.
Source: Wikipedia — Stained glass windows of Chartres Cathedral (CC BY-SA 4.0)