Suger’s window was not distinctively Gothic in its appearance. It no longer has its original form, but a mid-19th-century drawing by the restorer Viollet-le-Duc indicates that it had a very large ocular space at the centre, the glass supported by an iron hoop, and surrounded by simple semicircular cusped lobes cut out of flat stone in a technique known as "plate tracery". The window now has Gothic tracery in it, possibly added by Viollet-le-Duc who was very concerned about the lack of stability of the whole façade, and having restored the towers, was impelled to demolish the northern one when it suddenly subsided.