Navajo Bridge (left) crosses the Colorado River's Marble Canyon and was built in 1927-29.
At that time it was the only roadway crossing of the river and the Grand Canyon for nearly 600 miles (970 km).

In 1994 a new bridge (right) was constructed entirely for vehicles, while the historic bridge remained and serves as a pedestrian one.

JULY 2011 CHALLENGE: ARCHITECTURE IN BLACK AND WHITE