Your comment reminded me about the concrete arrows deployed across the U.S. for pilots.

https://www.atlasobscura.com/articles/before-radios-pilots-n...

According to that, Montana still uses them.

Reminds me that there were a number of planes that landed accidentally on the runway of an Air Force base close to Heathrow, apparently because it shared some similar landmarks, some kind of gas tanks the pilots were using as waypoints:

https://simpleflying.com/pan-am-707-raf-northolt/

Unfortunately, they de-commissioned the airway beacon system as an official navaid and stopped maintenance for the ground markers during the pandemic. Most are still there, but unlighted and unmaintained. A limited few are being operated by a historical society.

https://www.mdt.mt.gov/aviation/beacons.aspx

Absolutely unbelievable there's not an overhead picture in that article.