Hikers often stumble upon the unusual concrete markers and wonder why they were built . The first of these was erected in 1954 by a group called Friends of the Palisades Interstate Park Commission. They lay at the bottom of lit beacons and showed pilots the direction to fly in to arrive at the next air field . While they are no longer used , many lie forgotten until they are found by arrow-hunting fans .
Hikers often stumble upon the unusual concrete markers and wonder why they were built . The arrows directed the first air mail planes across the US to deliver post . They lay at the bottom of lit beacons and showed pilots the direction to fly in to arrive at the next air field . While they are no longer used , many lie forgotten until they are found by arrow-hunting fans .