Chartres Cathedral — rose window
Early 13th century stained-glass window in Notre Dame de Chartres Cathedral, France. Taken in May 2007. No tripod.
From Wikipedia article about Chartres Cathedral:
Dating from the early 13th century, the glass largely escaped harm during the religious wars of the 16th century; it is said to constitute one of the most complete collections of medieval stained glass in the world, despite "modernization" in 1753 when some of it was removed by well-intentioned but misguided clergy. From the original 186 stained-glass windows, 152 have survived. The stained glass windows are particularly renowned for their vivid blue colour, especially in a representation of the Madonna and Child known as the Blue Virgin Window (Pictured).