The Staufenmauer is a 60-metre stretch of the original 12th-century city wall built under Emperor Frederick I Barbarossa — one of the very few pieces of pre-Gothic Frankfurt still standing above ground. The section, of rough red Main sandstone, runs along Fahrgasse near the Konstablerwache, and survived because it was incorporated into the back walls of later houses. After 1944 air raids cleared the houses, the wall was conserved as a free-standing monument.
It is easy to walk past without noticing. Look for the explanatory panel at the eastern end, then trace the line of the old fortification — towers projected outwards every 50 metres, and the foundations of one of the gate towers can still be seen embedded in the modern pavement at the corner of Fahrgasse and Töngesgasse.