If you walk through Paris, you might notice stunning residential buildings with no glass in the windows. What are they?

The façade’s “windows” may be blind

Some Paris apartment façades include blind windows: openings or window-shaped panels that do not look into a room. They may be bricked up, covered with a solid panel, or painted to resemble glass and frames. From the street, they preserve the orderly pattern of the façade; from inside, there is no usable window behind them.

Why keep a window that does not open?

Many traditional façades were designed around repeated rows of openings. That regular rhythm helps a long stone elevation read as one composed design, rather than a jumble of rooms with differently placed windows. If a room layout, adjoining structure, or later alteration leaves one position without a real window, a blind one can keep the exterior pattern intact.

Some apparent “windowless” openings are also simply part of a building’s changing history: an opening may have been filled in, or its original window removed during repairs. A painted imitation is a different case—it is a façade detail, not evidence of a hidden room.

So the clue is not that the building has no windows at all, but that its exterior design and its interior plan do not always match one for one. The blank opening helps the street-facing façade stay visually balanced even when the space behind it has changed.