LI´MITES ROMA´NI sometimes simply LIMES or LIMITES,is the name generally applied to the long line of fortifications constructed by the Romans as a protection of their empire, or more directly of the Decumates agri, against the invasions of the Germans. It extended along the Danube and the Rhine, and consisted of forts, ramparts, walls, and palisades. The course of these fortifications, which were first commenced by Drusus and Tiberius, can still be traced with tolerable accuracy, as very considerable portions still exist in a good state of preservation. Its whole length was about 350 English miles, between Cologneand Ratisbon. It begins on the Danube, about 15 miles to the south-west of Ratisbon, whence it proceeds in a north-western direction under the name given to it in the middle ages of the Devil's Wall(Teufelsmauer), or Pfahlrain. For a distance of about 60 miles it was a real stone wall, which is still in a tolerable state of preservation, and in some places still rises 4 or 5 feet above the ground; and at intervals of little more than a mile, remnants of round towers are visible. This wall terminates at Pfahlheimin Würtemberg. From this point it proceeds in a northern direction, under the name of Teufelshecke(the Devil's Hedge), as far as Lorch, and is more or less interrupted. From Lorchonwards it does not present a continuous line, its course being effaced in many parts ; but where it is visible it generally consists of a mound of between 6 and 7 feet in breadth, sometimes rising to the height of 10 feet; and on its eastern side there runs along it a ditch or trench, which is called by the people the Schweinegraben, perhaps a corruption of Suevengraben(Ditch of the Suevi). In this state the limes runs as far as the Odenwald, from which point it changes its character altogether, for it consists of a succession of forts, which were originally connected by palisades. (Spart. Hadr. 12.) Remains of these forts (castella) are seen in many parts. At Obernburgthis line of fortifications ceases, as the river Mainin its northern course afforded sufficient protection. A little to the east of Aschaffenburg, where the Maintakes a western direction, the fortifications recommence, but at first the traces are not continuous, until some miles north of Niddait reappears as a continuous mound raised on a foundation of stones. This last part is now known by the name of the Pfahlgraben, and its remains in some parts rise to a height of from 10 to 12 feet. It can be distinctly traced as far as Rheinbreitbach, in the neighbourhood of Bonn, where every trace of a northern continuation disappears behind the Siebengebirge. It is probable, however, that it was continued at least as far as Cologne, where Tiberius had commenced the construction of a limes. (Tac. Ann. 1.50.) Some have supposed that it extended even further north, as far as the river Lippeand the Caesia forest; but from Tacitus ( Germ. 32) it seems clear that it terminated near the river Sieg.
This enormous line of fortification was the work of several generations, and the parts which were first built appear to have been those constructed by Drusus in Mount Taunus. (Tac. Ann. 1.56; Dio Cass..) But Tiberius and the other emperors of the first century constructed the greater part of it, and more especially Trajan and Hadrian. (Vellei. 2.120; Dio Cass.; Eutrop. 8.2; Spart. Hadr. 12.) Until the reign of Alexander Severus these limites appear to have effectually protected the Decumates agri; but after that time the Alemanni frequently broke through the fortifications. (J. Capitol. Maximain. 13; Flav. Vopisc. Prob. 13.) His successors, Posthumus, Lollianus, and Probus, exerted themselves to repair the breaches; yet after the death of Probus, it became impossible to prevent the northern barbarians from breaking through the fortifications; and about the end of the third century the Romans for ever lost their possessions in Germany south of the limes. (Comp. Wilhelm, Germanien, p. 290, &c. Buchner, Reise auf der Teufelsmauer, Regensburg, 1820.)
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