Among the windows made originally for the cathedral are several in the choir chapels, a large cycle of kings in the clerestory and several in the north nave aisle.
Original glass, notably from the triforium and choir chapels, was removed in the 18th century in the course of a redecoration program that replaced colored windows with white glass.
The five windows of the original south aisle of the nave were also removed at an unknown date. With the renewed interest in Gothic art during the 19th century, medieval glass from several secularized Cologne parish and monastic churches was incorporated into the glazing of the cathedral, mainly in the north transept and sacristy.In many windows coats of arms help both to identify their patron and to date the glass: for example, the arms of Heinrich von Virneburg in the cycle of kings in the clerestory help to date them to his archiepiscopate between 1304 – 1332.