The Small European Postal Administration Cooperation (SEPAC) is an organization that brings together Europe's small postal administrations or operators. SEPAC's goal is to promote philately and ensure the continued use of postage stamps in the face of other means of postal franking. For the joint issue of the participating members, the theme that was chosen was the most beautiful landscapes of the different countries. P&T Luxembourg has opted for Luxembourg City's Chemin de la Corniche for its SEPAC 2011 stamp.
The Chemin de la Corniche, often referred to as "Europe's most beautiful balcony", was built along the ancient fortification walls bordering the Alzette River and leads to the impressive Grund Gate.