Opposite the mouth of the Gailsbach valley is Rheindiebach. The ruins of
Fürstenberg Castle, a former toll station built by the Elector of Cologne in 1220
and destroyed in 1689, tower above the little village on the Rhine. The ruined
castle and its fortified tower reflect the history of the area and are well worth
visiting. They have been carefully restored to their original splendour over the past few years. Rheindiebach is first mentioned in 1461 as “Dyepach Ryne,
Niederdieppach”. Historians think the later prefix “Rhein” was added when the
settlement achieved economic independence. In 1669 the village is referred to as a “small town”, whereas in 1815 it has become a “hamlet”. Today the village
belongs to the community of Oberdiebach. It has about 1000 residents and covers an area of 885 hectares.