Vernaburg, Medieval castle in Salzkotten, Germany.

Vernaburg is a castle built on two square islands, each about 75 meters across, connected by a causeway and surrounded by water moats fed by the Heder river. The layout creates a distinct island setting within the landscape.

Wilhelm von Krewet built the castle in 1607 as a fortified residence. It later served as a military stronghold during the siege of Salzkotten in the Thirty Years' War.

The name Krewetburg recalls the Paderborn ministerial family Krewet, counted among the cathedral chapter's "Four noble stewards and pillars". Wilhelm von Krewet founded the castle in 1607 to move his seat here from the Freiheit in Salzkotten. After the male line died out in 1638, the estate passed to the von Brenken family.

The ruin lies at Krewetstrasse 3 in the Verne district of Salzkotten, in the Paderborn district of North Rhine-Westphalia. It is a listed architectural monument, but the grounds are privately owned and not open to the public, so visitors can only view the remains from the outside.

In 1990 a round Gothic residential tower was found near the ruin, long after the castle had been described as a ruin in Seven Years' War records. The tower's discovery shows that parts of the site predate the 1607 castle and had been forgotten.