Thank you, ulysses / Herbert - for the 'Like' to my night image. What you see here are ramparts / Festungswall and the moat / Burggraben that surrounds the old town of Fredrikstad (founded 1656) as protection and fortification (Schutz und Abwehr) against the Swedes in the Nordic war from 1700 – 1721 between Denmark-Noway, Sachsen–Poland, Russia, Preussen and Hannover on the one side and Swedens army under Karl 12. / Charles 12th (the war-king of Sweden) on the other side.