"Finding Nirvana is like Locating Silence" Jack Kerouac- Dharma Bums
The Navajo Bridge crosses the Colorado River at Marble Canyon. It is important for a couple of reasons. First, it is the official start of the Grand Canyon. Second, this bridge allows for one of only 7 land crossings of the Colorado River for over 750 miles. There are actually two bridges next to each other. The smaller one was completed in 1929, but now serves as a pedestrian bridge. The second, larger bridge, now handles all of the auto traffic and was completed in 1995.
The pedestrian bridge on the left sits 464 feet above the river and I have actually bungee jumped off of it. There are some good videos on YouTube that give you an idea of the scale. Unfortunately, I did mine at night so there is no video evidence.