Glenwood Canyon is on I-70 in western Colorado, about 150 miles west of Denver and 90 miles east of Grand Junction. The 16 mile-long canyon is on the Colorado River between the towns of Glenwood Springs and Gypsum. A huge engineering challenge was undertaken starting in the 1980s to complete one of the last stretches of Interstate Highway through the canyon. Transportation, environmental, recreational and economic considerations all had to be taking into account before the completed highway opened in 1992. In the end, the canyon ended up with a freeway snaking through its length using bridges, tunnels and retaining walls to create a highway that did not hurt, and even contributed to, the canyon's appearance.
There is also a pic of the lava cliffs at RMNP and Nick posing on the Grizzly Creek.