Burg Frauenstein, Medieval castle ruin in Bad Lauterberg, Germany.

Burg Frauenstein is a ruined medieval rock castle on the Frauensteinklippe, a tower-like dolomite crag on a hilltop between Scharzfeld and Bad Lauterberg. A ring wall encloses a core castle of about 10 by 25 metres within a plateau of roughly 65 by 45 metres. A ditch lies to the north and northeast, and a cellar vault from the Seven Years' War survives in the southern ring wall.

No medieval records name Burg Frauenstein; its position 300 metres southwest of Scharzfels suggests it shared that castle's ownership under the Guelphs, enfeoffed to the counts of Scharzfels and later Hohnstein until 1593. Beam supports and 14th-century pottery show medieval use. After 1596 Duke Heinrich Julius expanded it as a fortress. In 1761 French troops took it, allegedly by betrayal, bombarded Scharzfels from it, and blew it up; drill holes remain on the northwest side.

The name Frauenstein refers to the dolomite rock itself, the Frauensteinklippe, not to a woman associated with the castle. In 1761 French troops reportedly took the site by betrayal before shelling Scharzfels from it. Visitors can still see boreholes on the northwest side of the rock, left by the French demolition.

The site is open for visitors to explore at their own pace without formal restrictions. Sturdy footwear is recommended due to uneven ground, and care should be taken on steeper sections of the ruins.

The French troops who took the site in 1761, reportedly by betrayal, blew it up after Scharzfels surrendered on 25 September 1761; drill holes from that demolition can still be seen on the northwest side of the dolomite rock.