The Dortmund–Soest railway is a line in the German state of North Rhine-Westphalia. It runs from Dortmund Hauptbahnhof through the southern Dortmund district of Holzwickede to Unna and from there through the Hellweg Börde parallel to the Haarstrang ridge on the southern edge of the Westphalian Lowland via Werl to Soest. As the line was opened in 1855, it is one of the oldest railways in Germany.