Same place, looking from the restaurant down to the Danube-Oder Canal, or at least what’s left of it. It was an old idea from early renaissance: being able to go by ship across Europe. Through Bavaria, Austria, Hungary, Serbia, Bulgaria and Romania, river Danube connects middle Europe with the Black Sea, and then through the Bosporus with the Mediterranean.
River Oder has its source in Czechia, and from there runs north. As Poland moved west as a result of WWII, river Oder became a large part of the border between (then East-)Germany and Poland. The canal would have opened a connection between the Mediterranean and Northern Germany, Scandinavia and England.
Needless to say that it was too grand an idea to be realized. On the other hand, no idea could have been too grand for the Nazis to not try it. Try they did and … of the planned 320 kilometers, they managed to dig around four. Still, a beautiful result.