HNoMS Mjlner was the fourth of five ships of the John Ericsson-class monitors built for the Royal Swedish Navy and the Royal Norwegian Navy in the mid-1860s. Impressed by the use of ironclads during the American Civil War the design was based on that of the USS Monitor. They were designed under the supervision of the Swedish-born inventor John Ericssoncoincidentally designer of the Monitor and built in Sweden. Given a list of categories: company, educational institution, artist, athlete, office holder, mean of transportation, building, natural place, village, animal, plant, album, film or written work, what category does the paragraph belong to?
Mean Of Transportation