Roadside cave is a small lava tube in the Coconino National Forest in Arizona. 

The region is layered with basalt so there are numerous lava tube caves in the Coconino that range from a small room to passages that exceed over a mile in length.

Roadside cave is basically a room with two small ending passages and some artifacts that appear to be more like items that were left behind that include a barrel, wood, and some broken seats.

The Lava tube caves in the area are kept in secrecy so if you are interested in learning more about these and other caves, contact your local caving grotto for more information.