I thought we might leave North Africa for awhile (while wishing North Africans success in their bid for greater freedom) and look at a few bridges of the American Southwest.
It's fairly straightforward to build a bridge over a canyon. Just dig deep notches for the supports and build towers to support the cantilever spans until they meet over the canyon.
There's actually two Navajo Bridges across Marble Canyon. This one was completed a few years ago. We'll look at the older bridge tomorrow.
Arizona's Bridges: Navajo Bridges (1) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.