Already in the Middle Ages Gouda was familiar with the phenomenon of 'stained glass'. Some very old cartons which are present in the church, almost certainly prove that they served for glass. Unfortunately they got lost during the church fire of 1552. When the church was rebuilt again, a new and much larger series of glasses was created in a period from 1555 to 1603. Of all these glasses are the original designs in actual size (cartoon) have always been kept in the church, except during the Second World War when they were hidden in Gouda bank safes. When placed in a square they occupy an area of approximately 1159 m². During restoration they are always consulted, so the glasses look like they are brand new. But this also implied the cartons wore out. In the past they were only repaired when necessary, but now preservation work has been going on since 1985. From 2004 this has taken place in an accelerated pace in a studio in adjacent Museum Gouda. Six restorers work in diverse groups with the restoration on display to the public from Tuesday till Friday including a fascinating video presentation. All restored cartons are exhibited in alternating arrangements on the walls of the museum, so they can be admired with a closer look.