Sparrenberg Castle, Restored fortress in Bielefeld, North Rhine-Westphalia, Germany

Sparrenberg Castle is a restored fortress on the Sparrenberg hill above Bielefeld's centre. A long grey stone wall curves around a grassy upper level; at its left stands a low round tower with a flat top, beside it a taller slender round tower with a dark conical roof, and next to that a white-walled building with a red roof and red-framed windows. The counts of Ravensberg built the castle before 1250, and its present form comes mainly from the 16th and 19th centuries.

The castle was built before 1250 by the counts of Ravensberg to secure an important mountain pass in the region. It played a role in controlling local trade routes during the medieval period.

The name Scherpentiner, given to the western bastion, is documented only at the Sparrenburg; it derives from the serpentine, a light 15th- and 16th-century artillery piece. The Hermannsweg long-distance trail runs through the grounds directly in front of the castle, and the 31.5-metre tower can be climbed.

The grounds are freely accessible year-round, and reaching the castle involves walking up paths and stairs to the courtyard. The underground rooms can be explored with local guides to fully understand the passages and chambers.

The name Scherpentiner, given to the pointed bastion at the west corner, is documented only at the Sparrenburg; it derives from the serpentine, a light 15th- and 16th-century artillery piece. The Italian fortress master Alessandro Pasqualini designed it from 1556, integrating the earlier gun tower as its flank.