The Rhaetian Railway, abbreviated RhB, is a Swiss transport company that owns the largest network of all private railway operators in Switzerland. Headquartered in Chur, the RhB operates all the railway lines of the Swiss canton of Grisons, except for the line from Sargans to the cantonal capital, Chur, which are operated by Swiss Federal Railways (SBB CFF FFS), as well as the line from Disentis/Mustér to the Oberalp Pass and further on to Andermatt, Uri, which is operated by Matterhorn Gotthard Bahn (MGB). Inaugurated in 1888 and expanded from 1896 onwards in various sections, the RhB network is located almost entirely within Grisons, with one station across the Italian border at Tirano.

Chur is the capital and largest town of the Swiss canton of the Grisons and lies in the Grisonian Rhine Valley, where the Rhine turns towards the north, in the northern part of the canton. The city, on the right bank of the Rhine, is reputedly the oldest town in Switzerland.