Burg Hammerstein, Medieval castle ruins in Rhineland-Palatinate, Germany.

Burg Hammerstein is the ruin of a hilltop castle on a 195 m above sea level rise south of Hammerstein, overlooking the Rhine. Its ring wall survives, and a watchtower ruin still stands above the river. The site is reached by a small path off the Rheinsteig.

The castle was founded in the 10th century by the Conradines and soon became an important imperial fortress of the Holy Roman Empire. By the 11th century it played a central role in regional power struggles and conflicts.

The name Hammerstein comes from the noble family of the Burgraves of Hammerstein, who lived and ruled here until about 1417, when their genealogical trace disappears. The best-known episode is the Hammerstein marriage: Otto von Hammerstein kept his distant relative Irmingard as his wife against the ruling of the 1018 imperial diet, which the church did not recognise. The castle is also linked to the imperial regalia, kept here by Henry IV and later by Henry V.

You can reach the ruins via hiking paths connected to the Rheinsteig trail with good views along the way. The walk takes some effort but rewards you with sweeping views across the valley once you arrive.

Emperor Henry IV stored the imperial regalia here in 1071, a fact that shows how much trust the rulers placed in this fortress. Such valuable objects were brought here because of the castle's reputation for safety and strong defense.