[MisterJJ]

I like to do a "flyover" of a route with Google maps and look for interesting things near the route.

That's how I stumbled across one of these: https://sometimes-interesting.com/concrete-arrows-and-the-u-s-airmail-beacon-system/

 

[MisterJJ]

Here is a can't miss:
View attachment 45913

Been there. It's kinda creepy. I think there's a university research group operating there now. In my many trips between San Diego and Vegas I made a lot of little side trips along the way.

This is cool too:

Lava Tube - Mojave National Preserve (U.S. National Park Service)
Road is really rough though.