North-East Rhineland-Palatinate makes up the area to the east of the Rhine and covers part of the Lahn Valley and the Westerwald. Cities Bad Ems — a spa town on the river Lahn Betzdorf Hachenburg Katzenelnbogen — known for the castle of the same name Lahnstein — a fresh-air spa city with spa facilities and thermal baths Montabaur — known for its strikingly yellow castle Nassau — the Nassau Castle is the ancestral seat of the counts of Nassau and the Dutch royal family Rengsdorf — a well-known ""air spa" with popular forest walks Other destinations Understand Get in Get around See Do Eat Drink Stay safe Go next Middle Rhine Valley North Hesse