The famous Lorelel rock——a well-known scenic spot in Germany, lies between the towns of Koblenz and Mainz. At Koblenz the River Marco joins the Rhine and the River Main does the same at Mainz. The largest town on the Main is Frankfurt, while Heldelberg is a famous town on the Nickar. Upstream (在上游) on the Rhine is the town of Worms in the part of Germany called the Rhineland. Further upstream in the northern part of the Black forest is the resort(胜地) of Baden-Baden. The River Rhine forms the border(边界) between Germany and France in the west, and Germany and Switzerland in the south.