One of Europe’s most picturesque trips is a boat ride down (north) on the Rhine River, from Rudesheim to Koblenz, part of the ‘Middle Rhine’ (from Mainz to Cologne). Between these two destinations there are about twenty-five castles and more charming villages. Tour boats share this part of the river with large cargo barges, cross-river ferries and smaller pleasure boats. Some of the castles have been here since the 12th century. The length of the Rhine River is 1320 kms.
The Rhine and the Danube formed most of the northern inland frontier of the Roman Empire and, since those days, the Rhine has been a vital and navigable waterway carrying trade and goods deep inland. It has also served as a defensive feature and has been the basis for regional and international borders. The many castles and prehistoric fortifications along the Rhine testify to its importance as a waterway.
Most of the castles are not properly identified here. If you want more informaiton buy the map.