English: The Upper Germanic Limes, along with the Rhaetian Limes or simply "the Limes", was the border between the Roman Empire and the unsubdued Germanic tribes.

The Limes extended from the North Sea at Katwijk in the Netherlands along the Rhine to Eining (close to Kelheim) on the Danube. The total length was 568 km. It included at least 60 castles and 900 watchtowers.

Sansculotte/Wikipedia