|Fossa Carolina was a channel project planned to connect the Franconian River Rezat and River Altmuehl and thus to connect the large river systems of Rhein (Rhine), Main and Donau (Danube). In a way Fossa Carolina is the precursor of the Ludwigskanal (Ludwig Channel) and the Main-Donau-Kanal (Main Danube Channel). Fossa Carolina had to get over the European watershed.|
In 793 Karl der Große (Charlemagne) ordered to dig a 3,000 metres long channel to supply his troops in the war against the tribe of the "Awaren” which had attacked Bavaria in 788.
Some contemporary chroniclers wrote that the project finally failed. Others maintain that Karl succeeded in his channel plans. If we believe in the documents of these chroniclers Karl’s fleet was sighted near Frankfurt/Main in 794. This would be a proof for the completion of the Fossa Carolina.
At that time channel constructions consisted of number of separated ponds which were bounded by dams and dikes. To get over the different levels rolls and chutes were used. Today only a 500 metres long part of the original channels is still preserved and goes up NE to the railway track.