The bridges are over the Colorado river on US 89A. The old Navajo bridge is to the left. It is the 9th highest bridge in the US. It was completed in 1929. The new bridge was built as a replacement in 1995. It was deliberately built to look like the original bridge.

There is an interpretive center beside the road. These days you can walk on the old Navajo bridge across the river.

https://en.wikipedia.org/wiki/Navajo_Bridge