In New England, hidden in plain sight, there are some 100,000 miles (that’s about four times around the Earth) of centuries-old stone walls dotting the landscape, hidden amongst the forests and hills of the countryside! The walls weren’t really meant to be barriers or boundary markers, but rather a convenient way for plowing farmers to move rocks out of the way. “To learn more about these structures, the New England Department of Environmental Services launched a crowdsourced initiative to map every stone wall in the state, using Light Detection and Ranging (LiDAR) mapping. LiDAR utilizes lasers to produce geological surveys showing land elevation. Through an interactive interface known as the New Hampshire Stone Wall Mapper, interested parties can map the plethora of walls from the resulting aerial imagery.” [Source: Atlas Obscura]
Click here for a fascinating interactive Story Map that explains it in excellent detail.