The Limes Germanicus (German Frontier), a line of forts, formed a barrier between the Roman Empire and the Germanic tribes between 83 and 260 A.D. It extended from near Bonn on the Rhine to near Regensburg on the Danube, over 550 kilometers. The map on the souvenir sheet issued in 2007 by Germany covers the Limes of Germania Superior, from the Rhine to the Main near Regensburg. In 2005 the remnants of the Upper Germanic and Rhaetian Limes were inscribed on the UNESCO list of World Heritage Sits.
      The purpose of the Limes was not to prevent German tribesmen from entering the Roman Empire, but rather to control the traffic by bringing those who sought to cross to the attention of the Romans and provide a warning of possible attack.
     The building on the stamp is the Saalburg, a Roman cohort fort reconstructed as a museum of the Limes near Frankfort.