aerial view of furstenberg castle over the rhine river near rheindiebach with circular keep , curtain walls and artificial ditch

architecture halftimbered furstenberg picturesque traditional attraction palatinate landscape rheinland rhineland undefined building charming contrast fortress heritage hillside historic landmark medieval romantic stahleck vineyard germany history castles tourism castle cruise europe german gothic travel unesco valley ruine gorge pfalz rhein rhine river round tower stone blue burg site tour old sky