From the 200-m-long bridge also known as the Passerelle (footbridge, even though it's also open to road traffic), which spans the Pétrusse valley, you'll have a first glimpse of the rocky ledges—partly natural, partly man-made—on which the city was founded. The Pétrusse, more a brook than a river, is now contained by concrete, but the valley has been made into a singularly beautiful park.
Between av. de la Gare and bd. F.D. Roosevelt, Luxembourg City, Luxembourg