Channel Tunnel | tunnel | The Time Tunnel | Holland Tunnel | Fréjus Rail Tunnel | wind tunnel | Memorial Tunnel | Gotthard Road Tunnel | Severn Tunnel | Queensway Tunnel | Fréjus Road Tunnel | Thames Tunnel | Oslo Tunnel | Mont Blanc Tunnel | Lincoln Tunnel | Clyde Tunnel | Brooklyn–Battery Tunnel | Tunnel über der Spree | Tunnel | Ted Williams Tunnel | Tauern Road Tunnel | North Cape Tunnel | Malpas Tunnel | Lyttelton road tunnel | Khun Tan Tunnel | Gotthard road tunnel | Fréjus road tunnel | Disley Tunnel | Dark at the End of the Tunnel | Channel Tunnel Act 1987 |
Hill was especially impressed by Switzerland's Axenstrasse, a road built along Lake Lucerne in 1865 that included a windowed tunnel, and wanted to build a similar scenic highway through the Columbia River Gorge.