- A cairn is a human-made, often conical pile of stones used primarily as a landmark, trail marker, or memorial - Originating from Scottish Gaelic and Irish, these structures have been used for centuries to mark mountain summits, burial sites, and trails - They are also symbolic of peace and meditation - In southern Arizona, notable cairns include public art installations featuring large granite boulders, as well as historically significant, yet often controversial, trail markers in areas like Saguaro National Park - These structures represent both artistic, navigational, and, in some cases, unauthorized and damaging human-made stacked rock creations, in natural landscapes