Diesel House is a small industrial museum built around a huge Burmeister & Wain diesel engine that was once the largest of its kind in the world. The exhibits focus on diesel technology, ships, and Copenhagen's engineering past, with retired B&W workers often giving the place a personal edge.
It is a specialist stop rather than a headline Copenhagen museum, but it is worth seeking out if you like machinery, maritime history, or places where old industrial Copenhagen still feels close.