Sonnenstein, Hilltop viewpoint in Eichsfeld, Germany.

Sonnenstein is a 486-meter-high hill in the Ohm Mountains, characterized by steep limestone cliffs on its western side and an open, treeless summit. The location between Ecklingerode and Holungen provides clear views across the surrounding countryside.

After the fall of the Thuringian kingdom, this hill served as a boundary marker between different populations, separating the medieval regions of Liesgau and Eichsfeld. A fortified structure called Urbenschanze was later built to reinforce this border position.

The name comes from the roughly 20-metre-high, almost vertical Muschelkalk rock face on the western edge, which gave the hill its name. Until the 18th century the area around the hill was mostly called Graseforst, while the hill itself was simply der Stein; the name Sonnenstein only became usual in modern times. The hill also gives its name to the small settlement of Sonnenstein and the municipality of Sonnenstein.

The L1011 (Ecklingerode–Holungen) and L1012 (Worbis–Jützenbach) run past the foot of the hill; the wooded northwest slopes and the open summit are reached on foot. The 14-metre skywalk opened in 2017 projects 9 metres beyond the cliff edge, and the ground below the platform drops to almost 100 metres. An information board on the treeless dome explains the limestone grassland vegetation.

The 14-metre Skywalk opened in 2017 on the western cliff face, projecting 9 metres past the rock edge. Beneath the platform the slope drops away at an angle to almost 100 metres below. The cross visible on the summit today was set up in 1990 beside an old stone table.