Hundreds of feet above the Black Canyon's raging Colorado River, the longest concrete arch in the Western Hemisphere is almost complete. In a month workers will finish construction on the arch support of the Hoover Dam Bypass bridge, open to the public in fall 2010.
The new 4-lane bridge, on Highway 93, will replace the busy road on Hoover Dam, alleviating bottle-neck traffic and high accident rates by providing a safer route from Phoenix to Las Vegas and allowing truckers to return to a major NAFTA traffic route.
The Arizona Republic calls the project an "epic marvel," given the difficulty of building on faces of sheer rock and project challenges of drastic weather, accidents and one worker fatality.
When the bridge is complete, it will be the third-highest bridge deck in the country. How's that for modern marvels?
See more photos of the bridge construction here.