Burg Monterberg, Medieval castle ruins in Kalkar, Germany.

Burg Monterberg is a vanished hilltop castle west of Kalkar, of which no wall remains. The fenced site lies in woodland at the end of Monreberg street; the Monterburg e. V. association, founded in Kalkar in 2014, works to research and preserve it.

The hilltop castle, successor to the 11th-century fortress Munna, was rebuilt around 1260 by the Counts of Cleves and for a time served as their main residence. In 1327 Count Dietrich IX founded the Marienstift in its outer bailey, moved to Cleves in 1341. From then it was mainly a widow's seat for the countesses, and demolition began in 1624.

The name Monterberg survives in the street Monreberg at the site and in the Monterburg e. V. association founded in Kalkar in late 2014, which works to research and preserve the former castle. The nearby town of Kalkar was founded around 1242 close to the castle.

The site is accessible on foot but lies in a wooded area that can be damp and muddy. There is no infrastructure at the location, so plan to spend time quietly exploring the fenced grounds.

Excavations have uncovered artifacts from different periods, including a belt fitting from the 5th century and a gold coin from the 7th century. These discoveries reveal that the land was inhabited long before the castle was built.