Burgruine Falkenberg, Medieval castle ruins near Zierenberg, Germany.

Burgruine Falkenberg is a medieval castle ruin near Zierenberg with preserved foundation walls and parts of the original fortification structures. The remains show the structure of a strategic fortress with recognizable defense buildings on the hilltop.

The castle was probably built in the mid-13th century by a branch of the Schartenburg-Malsburg family to block the Warme valley between Schartenberg, Großer Gudenberg and Kleiner Gudenberg. No documentary evidence survives, and it is said to have been destroyed after 1271 by Landgrave Henry I of Hesse. The family branch that took its name from Falkenberg withdrew to the Weser and died out in 1733.

The name Falkenberg passed to a branch of the Schartenburg-Malsburg family, which withdrew to the Weser after the castle's destruction and died out in 1733. A Mainz charter of 1303 mentions a castle called David near the Schartenberg, which W. Lange links to Falkenberg.

The site lies in the Malsburger Wald, about 2.5 km northwest of Zierenberg and some 750 m south-southeast of the Friedrichsaue hamlet, on the Falkenberg hill (361.6 m) above the Warme valley. Only wall and ditch remains survive, so follow the forest tracks and look for the earthworks rather than masonry.

The oval main mound measures only about 45 by 30 metres, roughly 265 square metres, so it could hold just a few buildings. A nearly circular hollow in the relief data may mark the site of the bergfried, and a similar hollow lies on the eastern outer bailey, half its size.