Burg Kühlseggen, Medieval castle in Weilerswist, Germany.

Burg Kühlseggen is a moated castle in Weilerswist whose oldest surviving parts, a medieval dwelling house and its corner tower, stand on a raised island. The main house has dark brick walls with white cross-shaped timber window frames and steep slate roofs; a small dormer pierces the roof of the long two-storey wing, and a narrow stone tower with a pointed roof rises at the left. Dense shrubs line the water ditch.

The fortress was built in the medieval period as both a defensive structure and residence for nobility. It maintained its role as a regional power center and underwent various modifications over the centuries.

The name Kühlseggen comes from "Cudilsheggin", the byname of Cologne ministerialis Gobelin, first documented in 1312. The Scheiffart von Merode turned the seat into a Landtag-capable knightly estate; since 1836 it has belonged to the von Eltz-Rübenach family, who still live there. The Vorburg is used for agriculture.

The castle is privately owned and lived in, so the interior cannot be visited. A circular path along the moat, fed by the Weilerswister Mühlenbach, allows an exterior view. The site lies directly on the A61 between Swist and Erft.

The castle sits at 105.5 metres above sea level, the lowest point in the Euskirchen district. Until the 19th century the complex stood on two islands, and iron fittings on the gate pillars still show where a drawbridge once linked the main castle to the outer bailey.