http://www.portlandhikersfieldguide.org/wiki/Mosier_Twin_Tunnels_Hike

Activity Notes

When the Columbia River Highway was built through this area in 1921, it was necessary to build two tunnels to get through a high rock point. The tunnels, with their windows affording views over the river, were a highlight of any road trip to the Gorge: they were inspired by the design of the Axenstrasse, on Lake Lucerne in Switzerland.

Other Information
Driving Distance from Portland 120 miles
Distance - Round Trip 8 miles
Expected Duration Car to car in one day
Relevant Maps CG19