Note: Do not rely on this information. It is very old.
Neckar
Neckar, a large tributary of the Rhine, rises near Schwennenburg, in the Black Forest, and after a winding course of 250 miles flows into the Rhine at Mannheim, being navigable for the lower half of its length. On its banks are Tubingen, Heilbronn, and Heidelberg. The district around produces fair wine, and is famous in legendary lore.