Marble Canyon bridges over the Colorado River, Arizona, USA

So good, they built it twice. Marble Canyon bridges, Arizona, USA

This part of the US state of Arizona, about 70 miles from the Grand Canyon, is cut off from the rest by the Colorado River and its deep canyons. On this day in 1995, the twin Marble Canyon bridges, better known as Navajo Bridge, were officially dedicated as the second bridge was installed.

The first, in place since 1929 when it was hailed as a 'modern marvel', had long been key to travel across the 834ft (254m) gap of Marble Canyon. But as time passed, the area saw heavier vehicles and more traffic. After much debate about the impact on Native land and endangered plants, and the likelihood of debris falling into the river below, plans were developed for the, nearly identical, second bridge.

Now, Marble Canyon (which is largely limestone, not marble) has two bridges, each about 470ft (143m) above the Colorado River. The original is used by humans and horses, while the new bridge carries vehicles. Both bridges hold the title of ninth-highest in the United States (although the newer one is actually about 3ft higher).