Burg Nesselburg, Medieval castle ruins in Nesselwang, Germany

Burg Nesselburg is a ruined hilltop castle at 1038 meters on the Kappelköpfel, a spur of the Alpspitz about 170 meters above Nesselwang. Its rectangular plateau measures roughly 30 by 23 meters. The north side held the palas, while the south retains a shield wall about 2.6 meters thick and up to seven meters high. The masonry mixes stream cobbles, Nagelfluh, sandstone and tuff, with corner blocks visible at the southeast corner.

The von Rettenberg family built the fortress in the late 13th century for the Lords of Nesselwang. In 1595, a fire damaged it so severely that it could no longer serve as a residence.

The name Nesselburg derives from Nesselwang, where the castle stood as the administrative seat of the Augsburg prince-bishopric's Pflegamt from 1350. After the 1525 Peasant War plundering, the site was made habitable again. Today the ruins are a destination for hikers on the Kappelköpfel, and the market of Nesselwang acquired the castle, waterfall, and Schlosswald in January 2025 to resume restoration.

The site is reachable by a hiking trail south of Nesselwang and sits on a mountain ridge in hilly terrain. Good footwear and some fitness are needed to visit the ruins.

The fortress used the natural landscape as a defense system: the eastern and western sides drop steeply into stream gorges. These natural cliffs formed an additional barrier that deterred attackers.