Grubenhagen Castle, Medieval castle ruins near Einbeck, Germany

Grubenhagen is a castle site on a hilltop near Einbeck featuring medieval remains including a round tower rising about 18 meters high. The fortress shows an oval-shaped inner ward surrounded by outer defensive ditches and ramparts.

The castle was probably built under Henry the Lion and is first documented in 1263, when the ministerialis family Grubo von Grubenhagen held it as Burgmannen. Around 1300 it returned to the Dukes of Brunswick-Lüneburg. In 1291 it gave its name to the Welf Principality of Grubenhagen founded by Henry the Admirable, though it was never the principality's residence; the dukes usually resided at Heldenburg or Herzberg. The name Grubenhagen for the principality only appeared around 1617.

The hilltop fortress served as the center of a medieval territory that controlled local trade and communication routes. Visitors can still see how the defensive structures were positioned to command the surrounding landscape.

The tower can be climbed but you must collect the access key from Rotenkirchen village beforehand. The site sits on a hilltop, so wear sturdy shoes and plan for a short walk uphill.

In 1448 Henry III of Brunswick-Grubenhagen holed up here after a raid near Hofgeismar. A coalition army of 16,000 men, 2,000 horsemen and 1,500 wagons besieged the castle; Göttingen sent two guns, the Makefrede and Scherpe Grete, the latter bursting during the fight. The besiegers failed and instead devastated Altendorf, Reinsen, Bensen and Rotenkirchen.