This is a very old unused black and white/sepia postcard of Rouen - L'Eglise Saint-Maclou. I have no idea of the exact age of the card, but it looks like it is from the very early 1900s.  The card is in very good condition – no creases (apart from a tiny scuff near the centre) or obvious marks (other than faint album marks), with only very slight scuffing to some corners.