This article is about the Class III road numbered C70 maintained by Argyll and Bute Council. For other roads numbered C70, see C70.
The C70's number is revealed in signage on the route
The C70 runs through Glen Fruin between Loch Lomond and Loch Long. However, it should not be confused with the military haul road, numbered as the A817, which runs higher up the glen. The C70 starts on the A818 near Drumfad above Helensburgh and runs north into the glen, crossing the river and running along the valley floor to the watershed above Faslane. It then drops steeply down through a series of switchback bends to meet the A814 by the military installation.