Burg Sternberg, Medieval castle in Extertal, Germany.

Burg Sternberg is a medieval hilltop castle in Extertal, North Rhine-Westphalia, built with a central keep, stone curtain walls, and a fortified inner courtyard. The complex sits on elevated ground that made it easy to defend and gave it a commanding view over the surrounding valley.

The oldest ring-wall foundations date to around 1100; Count Heinrich I of Sternberg built the stone residential tower around 1240, funded largely by salt revenues from Bad Salzuflen. In 1447 the castle withstood an attack by a 15,000-strong army of Archbishop Dietrich of Cologne. Simon VI of Lippe had the north tower converted into the Rittersaal by builder Hermann Wulff, and in 1733 the castle was pledged to the House of Hanover for 410,000 silver thalers before being bought back in 1781.

The castle houses the Klingende Museum, whose core collection of over 150 musical instruments comes from Peter Harlan, who settled here at the end of the war. Guided tours for pre-registered groups are the only way inside, as the castle remains privately owned and inhabited.

The castle sits on a hill and is reached on foot by a path that involves some uphill walking, so comfortable shoes are a good idea. It is worth checking in advance which parts of the site are open to visitors on any given day.

The castle houses the Klingende Museum, whose core collection of over 150 musical instruments comes from Peter Harlan, who settled here at the end of the war. The site is privately owned and still inhabited, so it is not freely accessible; guided tours are given to groups by prior arrangement.