Grillenburg, Medieval castle ruins in Grillenberg, Germany.

Grillenburg is a medieval castle ruin with visible remains of fortification walls built from large stone blocks and later brick additions. The site near Sangerhausen allows visitors to see different construction phases in the preserved structures.

The castle was built around 1217 as a knight's fortress and first appeared in records under the Archbishopric of Magdeburg. During conflicts between Halberstadt bishops, it served as a strategic military location in the region.

The castle reflects medieval military building techniques typical of the region, visible in its stone construction and wall layout. Visitors can observe how defensive structures were designed and built during this period through the remaining walls and foundations.

The site is freely accessible and offers views of the ruins from different angles around the walls. Visitors should know that the location is outdoors and conditions may vary depending on the season.

The ruin is listed as stamp point no. 208 in the Harzer Wandernadel system, a network of checkpoints hikers stamp in a booklet. The site lies on a 312.5 m hill within the Gipskarstlandschaft Pölsfeld nature reserve, part of the Karstlandschaft Südharz biosphere reserve, and is reached from Grillenberg, about 350 m northeast of the village church.