When you raft the mighty Colorado River, you can’t help but be awed by its dramatic deep gorges and white-water rapids. But there are noteworthy manmade sites, too, such as the Navajo Bridge over Marble Canyon. Look closely, and you’ll see it’s actually 2 similar bridges: one historic, from 1929, and one modern, from 1995. Located in Northern Arizona between the Grand Canyon and Utah’s Lake Powell, the span is one of only 7 land crossings over the river for 750 miles. Originally known as Grand Canyon Bridge, it was renamed in 1934 for the local Native American tribe.