The Isar River Valley Railway (German: Isartalbahn) is a standard gauge and electrified railway in the German state of Bavaria. Originally it was 51.1 km long, running from Munich South station to Bichl and was built from 1891 to 1898 in sections by the Lokalbahn AG company (LAG). The section from Munich South to Wolfratshausen was classified as a main line, while the section from Wolfratshausen to Bichl was classified as a branch line.