Bertradaburg, Medieval castle ruin in Mürlenbach, Germany

Bertradaburg is a ruined hill castle on a 348-metre rock spur above Mürlenbach in the Vulkaneifel. Its 30-metre double-tower gate, the former residential tower, is visible from afar. The site also preserves a 13th-century shield wall and a 16th-century southwest roundel five metres thick.

The castle is first documented in the 13th century as a state fortress of the princely imperial abbey of Prüm, though archaeological finds point to earlier fortifications on the site. Local tradition holds that Bertrada, Charlemagne's mother, lived here, suggesting his birth around 747. After French Revolutionary troops occupied and damaged Prüm Abbey from 1794 to 1802, the castle was secularised and auctioned to a private owner.

The name Bertradaburg points to Bertrada, the mother of Charlemagne, even though no confirmed historical link ties her to this specific location. The name has nonetheless shaped how the site is talked about locally for generations.

Reaching the ruins requires a walk up a hillside path, so a basic level of fitness is helpful. The ground is uneven in places and can become slippery after rain, so sturdy footwear is a good idea.

Parts of the ruined castle are available as overnight accommodation, which means some visitors actually sleep within the medieval walls rather than just passing through. This makes it possible to experience the site after all the day visitors have left and the place quiets down.