Thomas B
Google
In our view, the most impressive sandstone arch in the entire park, as well as the world. Here you are standing in front of the longest arch in the world, stretching an impressive 306 feet across at the base and a mere 6 feet in diameter at its narrowest point. This natural wonder is a must-see arch for anyone visiting Arches National Park. In 1991, a large slab approximately 73 feet long fell from beneath the arch and that is why no one can hike to the base due to safety concerns. Stunning arch.