 This transformation is highly apparent in the downtown core, which was rebuilt in the neoclassical style to resemble Saint Petersburg, mostly to a plan by the German-born architect C. L. Engel.As elsewhere, technological advancements such as railroads and industrialization were key factors behind the city's growth.Despite the tumultuous nature of Finnish history during the first half of the 20th century (including the Finnish Civil War and the Winter War which both left marks on the city), Helsinki continued its steady development.