Kahl-Burg, World War II bunker in Le Tréport, France.

Kahl-Burg is a German World War II command bunker dug into the chalk cliff above Le Tréport, entered by two steel doors from the street. Its 32 rooms on four levels are linked by 270 metres of galleries and 225 steps, with five openings toward the sea and town, three observation posts and two fighting posts. The concrete exterior carries the name "Kahl-Burg" in raised letters beside a brick-framed door.

The Kahl-Burg was built in 1942 by the Organisation Todt as part of the Atlantic Wall, in direct response to the Allied raid on Dieppe on 19 August 1942. About 200 forced labourers, mostly Ukrainian women housed in camps at Eu, worked 10- to 14-hour shifts; around 20 died and are buried in Eu. Work stopped in late August 1944, and Canadian marines took the fort on 1 September 1944.

The name Kahl-Burg, German for "bald castle", likely refers to the bare clifftop above the bunker. Inside, the walls are lined with clinker bricks, some laid enamel-side inward; a few still show their pale blue glazed surface. The entrance area holds a collection of militaria, and two rooms display museum cases.

The bunker is entered through two steel doors from the street; inside, 225 steps link the four levels and the average temperature stays around 10 °C, so bring a jacket. Guided tours for small groups are arranged by appointment with the Le Mur de la Manche association, and the site opens on 8 May, 11 November and the European Heritage Days.

The interior walls are lined almost entirely with clinker bricks, but the work stopped unfinished when the Allies landed on 6 June 1944. Workers were ordered to turn the pale blue tiles of the Hotel Trianon so the enamel face stayed hidden in the masonry; a few misplaced ones still show their glazed surface.