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.
Some windows survive from an earlier Chartres Cathedral, such as the three lancets on the west front (1145–1155, contemporary with those made for Abbot Suger at the Basilica of Saint-Denis) and the lancet south of the choir known as 'Notre-Dame de la Belle Verrière', famed for its Chartres blue (1180). However, most of the windows were probably made between 1205 and 1240 for the present church, taking in the Fourth Crusade (bringing a large number of important relics to Chartres) and the Albigensian Crusade, as well as the reigns of Philip II Augustus (1180–1223) and Louis VIII (1223–1226), with the building's consecration finally occurring in 1260 under Louis IX (1226–1270).