Grand Canyon Caverns

Twenty-five miles west of Seligman, a two-lane stretch of the Mother Road crosses empty plateau where cattle wander onto the tarmac after dark — and 210 feet under it lies one of the largest dry caverns in the United States. Dry is the key word: there is no water down there, so none of the dripstone — the stalactites and stalagmites — that other caves grow. Instead the still, 56-degree air has left rare aragonite crystals and a silence so complete that visitors report hearing their own heartbeat. The limestone itself was once the floor of an inland sea; the caverns were dissolved out of it by sulfuric acid rising from below.

The way in is pure Route 66. A woodcutter named Walter Peck, the story goes, nearly fell into the hole in 1927 on his way to a poker game, came back convinced the glittering walls held gold, bought the property, and — finding only fool's gold — began charging tourists a quarter to be lowered on a rope. The names changed over the decades, from Yampai to Coconino to Dinosaur Caverns, before Grand Canyon Caverns stuck in 1962. That year the federal government, mid-Cuban Missile Crisis, stocked the caverns as a fallout shelter with food and water for two thousand people; the rations are still down there, a Cold War time capsule the dry air has kept for sixty years. Above ground a 1963 motel offers the deepest hotel room in the country, a suite 220 feet underground.

The site's older history is Native, and it is not a sideshow. The natural entrance was sealed in 1962 at the request of the Hualapai, who hold it a sacred burial place — the caveman that early tourists paid to gawk at was in fact the remains of two Hualapai brothers who died in the influenza winter of 1917 and were buried in what was thought to be a shallow pit. The caverns sit at the edge of the Hualapai reservation, near Peach Springs, the tribal capital, and are today owned and operated by the Havasupai. Come for the strangest overnight on Route 66. Stay long enough to learn whose ground it is.