I visited this WHS in May 2020 as a long road trip after two months of lockdown. I visited both inscribed main locations starting with a visit just outside the town of Dannewerk (or Dannevirke) and then heading to Haithabu (or Hedeby).

Make sure to follow the brown sign to Dannewerk Museum not the yellow one to Dannewerk town. I parked for free near the small museum. It is possible to visit the 22 inscribed locations between Dannewerk and Haithabu completely free of charge and as such these are open 24/7. The small Dannewerk museum entrance costs 5 euros while the bigger Haithabu Viking Museum costs 8 euros to visit.

As is the case with all Viking Age sites, there isn't much to see apart from the ubiquitous earthwork mounds and ramparts as wood isn't a durable medium. That said, and after heeding Nan's advice not to expect much of this WHS, I still was positively surprised by the scale of the curved walls near Dannewerk, stretching for around 30 km and connecting Dannewerk and Haithabu between the Baltic Sea and the North Sea.

Dannewerk is a fortification constructed by the Danes in the Early to High Middle Ages to protect themselves against peoples from the South. It is an archaeological and cultural monument of European significance with elements of a historical cultural landscape which have almost disappeared elsewhere. A brick section of the 12th century curved walls concealed beneath the earth, grass and oak trees can be seen quite close to the museum. Being exposed to the elements, means that it requires constant restoration with more bricks and metal structures to reinforce the wall and prevent mudslides. The brick wall is believed to be one of the oldest brickwork structures in Northern Europe and certainly the oldest structure in this part of Germany.

King Valdemar the Great of Denmark had the wall built, which meant yet another phase of modernisation for Dannewerk. His intention was to defend the kingdom of Denmark from Slavic and Saxon raids as engraved on his tombstone. It was also a demonstration of his power aimed at the German king, even though I tend to agree with Nan who described him as a 'poor king' when compared to other kings. Further on from the brick wall is a reconstructed defensive fortification (perfect for drone photography) which is a relic of the German-Danish war of 1864 over the national affiliation of the Duchy of Schleswig. The Danes built 27 bastions for their cannons and modifying the medieval earthworks.

Next stop was the bigger parking lot of the Haithabu Viking Museum in Busdorf. Instead of heading left towards the big museum with metallic structures resembling the reconstructed wooden Viking structures of Trelleborg in Denmark, heading right will bring you at the massive semi-circular ramparts of the Viking Age commercial settlement and port of Haithabu which are also part of the pilgrimage route to far away Santiago de Compostela. Due to the several trees these ramparts are less easy to appreciate than those at Dannewerk. These ramparts were built by Danish king Harald Bluetooth in the second half of the 10th century who also ordered the connecting wall between Dannewerk and Haithabu afterwards.

Reconstructed wooden dwellings, similar to the pile dwellings in Unteruhldigen, are now located on the site believed to have been the town centre. Parallel to the banks of the pretty Haddebyer Noor lake, formerly a small arm of the Schlei inlet of the Baltic Sea, was a wooden plank road with paths towards the water leading to harbour jetties, which also served as a market place. Northwest of the settlement there were numerous workshops for various crafts, so much so that production waste such as  iron slag and glass was found there. Southwest of the settlement instead, there was quite a large cemetery.

At the end of the 11th century, Schleswig succeeded Haithabu, even though the abandoned trading centre was never built over and it is believed that as much as 95% of what remains is still underground waiting to be excavated. The area near Haithabu is much more scenic for a stroll than Dannewerk and it reminded me of the Hovgarden and Birka WHS in Sweden, albeit without any rune stone.

There are rather large rusty metal UNESCO inscription plaques in Dannewerk as well as Haithabu. The overall experience was quite similar to that of Kernave in Lithuania and as such the OUV, if any, is very difficult to grasp. However, since through this tick I completed Germany again and thanks to Nan, I rated my WHS experience with 2 stars.  

I had already visited the nearby WHS of Lubeck, Bremen, Speicherstadt and Wismar a couple of years before but in the meantime the Wadden Sea in Germany was added too so afterwards, again thanks to Nan's guidance, I also visited the German part near Husum, opposite the German Wadden Sea islands, during low tide (without the muddy walk many seem to make, so much so that a public shower is available at the end of the pier).