A landau is a coachbuilding term for a type of four-wheeled, convertible carriage. It is lightweight and suspended on elliptical springs. It was invented in the 18th century (first noted in English in 1743) and was named after the German city of Landau in the Rhenish Palatinate where they were first produced. Lord, Hopkinson, coachmakers of Holborn, London, produced the first English landaus in the 1830s.
Cook, Thomas & Son Cook's Handbook to Norway: With the Principal Routes to Sweden and Denmark Etc. (London, England: Ludgate Circus, 1901)