Falkenstein Castle, Medieval castle in Falkenstein, Germany.

Falkenstein Castle is a hill castle on a rocky ridge about 320 m above the Selke valley, built in Romanesque style between 1120 and 1150 and altered repeatedly since. Its inner bailey of roughly 40 × 40 m holds a 31 m bergfried with walls 8.5 m thick at 2 m height, now open as an observation tower. The photograph shows rough brown stone facades with a row of small arched openings, a half-timbered upper section, and a pale grey round tower under a dark domed roof with a lantern and weather vane.

The fortress was built between 1120 and 1150 by the lords of Konradsburg and later became the birthplace of the Sachsenspiegel, the first German law book. This legal text made the castle an important site in the history of German law.

Since 2006 the castle has hosted an annual summer "Minneturnier", a singing contest modelled on medieval minstrel competitions with performers from Germany, Austria, Switzerland and Italy. At the start of October the Burgfest takes place each year. The castle also appeared in the GDR children's series Spuk unterm Riesenrad and in the DEFA fairy-tale film Schneeweißchen und Rosenrot.

A signposted hiking trail leads to the castle from a car park 2 km away, and a small road train also runs along this route. The castle is checkpoint no. 200 of the Harzer Wandernadel stamp system. The site was closed from mid-January 2025 for renovation and reopened on 28 March 2026.

The castle's treasure was hidden twice by the Rothkirch brothers: part of the family hoard was buried at the Tormannswiese in 1943, more was walled into a windowless mezzanine of the Spinndiele in spring 1945. The buried cache was found in 1990, the hidden floor opened in 1992, yielding around 3,000 pieces including the Asseburg beaker. In 2017 builders found a cavity with Meissen porcelain, now shown in the museum as a loan.