The Königstein Railway (Königsteiner Bahn) is a 1902 opened, single-track and non-electrified secondary railway line that connects the town of Königstein im Taunus with the city of Frankfurt am Main on the southern edge of the Taunus in the German state of Hesse. The Regionalbahn line, which was also called the from 1989 to 1995, now runs from Koenigstein via Frankfurt-Höchst station as timetable route 646 to Frankfurt (Main) Hauptbahnhof.