Burg Blankenburg, Medieval castle in Wolfshagen, Germany

Burg Blankenburg is a ruined lowland castle on an island in the Haussee, surrounded by a water moat 6 to 9 m wide. Its keep, the 24 m Fangelturm, has an 11 m square base of fieldstones topped by a round brick section; parts of the castle wall also survive.

The von Raben family built the lowland castle on an island in the Haussee around 1250. From 1392 the lords of Blankenburg held it as a fief of the margraves of Brandenburg. In 1456 Elector Frederick II took the castle after the Blankenburgs fell into disgrace through feuds and robber-knight raids; they recovered the fief only through intercession, on condition of staying with Brandenburg. The Thirty Years' War left it a ruin.

The name comes from the von Blankenburg lords, who held the castle as a fief of the Margraves of Brandenburg from 1392. In 1456 Elector Frederick II seized it after feuds and robber-baron raids; the family regained it only by pledging loyalty to Brandenburg. The keep is called Fangelturm, "capture tower".

Burg Blankenburg stands on an island in the Haussee, surrounded by a 6 to 9 m wide moat that again carries water year-round. It lies by the B198 in Wolfshagen, on the Brandenburg–Mecklenburg-Vorpommern border. The ruin can be visited without a guide; the keep and parts of the wall are preserved.

The keep is called Fangelturm, or "capture tower", a name recalling its use as a prison. It rises 24 m: an 11 m square base of fieldstones topped by a round brick section. The surrounding moat, 6 to 9 m wide, was deepened in recent times so that it again holds water year-round.