Reading a château through its windows
Openings, frames and glass tell different parts of a building’s story. Look at them separately before deciding they belong to one moment.
Stand far enough from a château to see several windows together. Their rhythm may appear regular until one sill sits higher, one opening is narrower or a line in the masonry interrupts the pattern. These differences make good starting points for questions. They are less reliable as instant dates.
Separate the opening from the window
There are at least three things to consider: the opening in the wall, the frame fitted within it and the glass held by that frame. They need not be the same age. Treating them as one object can hide the history of alteration and repair.
Begin with a simple drawing of one elevation. Mark differences in width, height and spacing without assigning a century. Then look more closely at the junction between the surround and the adjacent wall. Record a change in material or jointing as a change, leaving its explanation open.
An alteration is part of the record
Fontainebleau's official record for the Aile des Ministres explicitly notes that its openings changed over the centuries. This is a useful reminder that the façade seen today is a historical result, not necessarily a single original design.
A blocked opening may relate to a changed interior, a different circulation route or another intervention. Deciding between those possibilities requires plans, photographs or building investigation. Symmetry alone cannot establish the sequence.
Look at glass without making it a dating test
Historic England identifies the materials, craftsmanship and design of old windows as sources of significance. Uneven reflections can invite closer attention, but appearance alone does not securely establish a pane's age or origin. Record what you see rather than labelling every ripple as original glass.
For a useful comparison, photograph the same window from outside and, where access is permitted, inside. The interior may reveal shutters, changes in the reveal or relationships to panelling that the façade conceals.
At the end of the visit, a good question is not simply “How old are these windows?” Ask instead which parts have remained, which have changed and what evidence could connect them.
Further reading
Fontainebleau: Aile des Ministres and Historic England: traditional windows. For the wider picture, read The beauty of an unfinished history.