The Iron Footbridge crosses the Main between the Römerberg and Sachsenhausen, and is the single most photographed view in Frankfurt: skyline towers on one side, the apple wine quarter on the other, and the river running underneath. Built in 1869, blown up by the retreating Wehrmacht in March 1945, rebuilt in 1946 with its original girders fished out of the river, and weighed down today by tens of thousands of padlocks left by lovers.
It is the natural crossing for a walk between the old town and the Museumsufer, takes about five minutes to cross slowly, and is open only to pedestrians and cyclists. Best at dawn before the river-cruise traffic begins, or after dark when the office towers reflect in the water. Free of course.