The cover shown here was sent from Luxembourg-Ville on August 31, 1925, by special delivery [EXPRÉS handstamp], to Madame la Comtesse van den Steen de Jehay, Dame d'honneur de S.H. la Reine des Belges, residing at the Château de Losange just south of Bastogne near the Luxembourg border, as seen on the map above. Countess Clotilde van den Steen was born on December 9, 1850 and lived until April 22, 1932. You will find a detailed description of the lovely Castle of Losange in the Belgian Ardenne, dating from the Middle Ages, at www.prov-liege.be/culture/jehay/jehay.htm. An image is shown below. In 2004, the population of the hamlet of Losange near the castle was just 30 inhabitants.
The cover is also of interest for its uncommon rate. During the short period from August 25, 1923 to October 1, 1925, a 25-centime 20 g letter rate and a 1.50-franc special delivery fee were in effect under the postal treaty between Luxembourg and Belgium. (From June 1, 1924 until October 1, 1925, France and Germany also enjoyed a 1.50-franc special delivery rate; however, the 20 g letter rate to these countries during this period was 30 centimes.) The franking appropriately is the 1-franc Vianden castle stamp used in combination with the blue 75-centime first issue G.D. Charlotte definitive, exactly paying the 1.75-franc postage and special delivery fee. The cover was backstamped at Bastogne the next day.