 His first projects of this time (including a project for a rebuilding of the house of the Blackheads), which were not executed, were historicist in style, drawing much inspiration from German Renaissance architecture.In 1908, Rosenbaum completed a project for one Reinhold Reichmann on the corner of the two streets Pikk and Hobuspea in old town, Tallinn.In this, the first building by Rosenbaum that was actually built, his eclectic style and love of ornamentation is already apparent.