From its source in Belgium, between Neufchâteau and Bastogne, the Sûre traverses the Grand Duchy up to the Moselle and the German border, tracing the frontier from Wallendorf to Wasserbillig. The upper valley of the Sûre is the most spectacular stretch, the river cutting deeply into the ancient Oesling massif. In contrast, the slopes of the lower valley become less steep and the prairies wider. Hikers take note, several trails have been waymarked.