The passes of the Alps have always had importance as the gates of
traffic from North Italy to the rest of Europe; some of them, such as
the two St. Bernard Passes, are under the protection of friendly monks;
but railroads have now been constructed to pass the great barrier by the
tunnels of Mont Cenis in the west, of St. Gothard in the center, and the
Simplon farther east (opened 1906), by a line over the Brenner Pass from
Innsbruck to Bozen, and by an eastern road over the Semmering from
Vienna to Graz.
Southward the Alps fall steeply to the low plain of Lombardy, but a mass
of lesser highlands and plateaus extends northward from them over
central Europe to the border of the plain of Northern Germany.