The Limes Germanicus (Latin for Germanic frontier) was a remarkable line of frontier (limes) forts that bounded the ancient Roman provinces of Germania Superior and Raetia, and divided the Roman Empire and the unsubdued Germanic tribes, from the years 83 to 260. At its height, the limes stretched from near Bonn on the Rhine to near Regensburg on the Danube.

The Limes Germanicus was divided into:
  • The Lower (Northern) Germanic Limes, which extended from the North Sea at Katwijk in the Netherlands along the Rhine;
  • The Upper Germanic Limes (just to be confusing, also called the Rhaetian Limes or simply "the Limes") started from the Rhine at Rheinbrohl (Neuwied (district)) across the Taunus mountains to the river Main (East of Hanau), then along the Main to Miltenberg, and from Osterburken (Neckar-Odenwald-Kreis) south to Lorch (Ostalbkreis) in a nearly perfect straight line of more than 70 km;
  • The proper Rhaetian Limes extended east from Lorch to Eining (close to Kelheim) on the Danube. The total length was 568 km (353 miles). It included at least 60 castles and 900 watchtowers.
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  1. Reconstructed Limes near Saalburg, Germany
  2. Reconstructed Limes watch tower, near Rheinbrohl
  3. Reconstructed Limes watch tower, Hillscheid
  4. Reconstructed Limes watch tower, near Kastell Zugmantel, Taunus
  5. Reconstructed Roman fort, Saalburg, near Bad Homburg