Altwartenburg, Timelkam, Medieval castle ruins in Timelkam, Austria.

Altwartenburg are castle ruins perched on a hill north of Timelkam, with stone walls and structures visible from multiple historical periods. The site displays typical features of a medieval fortification with sections of walls and foundation elements still standing.

The castle was built during the medieval period as a defensive stronghold controlling valleys and trade routes across the region. Over time it lost its military importance and gradually fell into ruins.

The ruins represent an important landmark for the local community and are recognized as a protected monument. Visitors walking through the area notice how the site connects people to their medieval past.

The castle area and all access paths are officially closed until further notice (as of 2020), so the ruins cannot be visited. The site lies at Altwartenburg in the municipality of Timelkam, on the municipal border with Vöcklabruck, on a hill left of the Vöckla. The neighbouring Schloss Neuwartenburg stands on the right bank of the Vöckla below the old castle.

During the Nazi period a forced-labour camp stood on the castle grounds, including a "Polenkinderlager" where children of forced labourers were born; at least 16 died, partly from inadequate care. The area hosted open-air events until 2010.