Just after passing through the series of blasted tunnels on a dirt road, you’ll find Elephant Rock and the first of two campgrounds nestled among giant boulders and the abandoned railway line. The first, on the left, is free primitive camping. There are no toilets, but the Arkansas River, nearby bolted climbs and massive mountain views are hard to beat.
Three miles past this spot is the Arkansas Headwaters' Railroad Bridge campground, which has a similar landscape, toilets and is better maintained. Neither site has water.
To get here, turn north on Colorado Ave off E Main St and keep going.