Rheingrafenstein Castle is a castle on a 136-metre-high (446 ft) porphyry rock formation, the Rheingrafenstein, known as Huhinstein a thousand years, on the river Nahe, opposite Bad Münster am Stein-Ebernburg in the district Bad Kreuznach.

It was definitely the ancestral castle of the Lords of Stein, the later Wild- and Rhinegraves, and it remained in their possession until the French Revolution.

After the battle of Sprendlingen in 1279, Siegfried II lost his possessions of the right bank to the Archbishop of Mainz.

During the Palatinate War of Succession, the castle was destroyed by French troops under general Mélac in 1689.

In 1835, descendants of the Wild- and Rhinegraves of Rheingrafenstein (who had been raised to princes in the meantime), bought the ruins back from the municipality of Münster.Parts of the enceinte, a vaulted cellar, a few steps of the former tower house, and the foundations of the former tower staircase are still standing.