Reminds me of a trip to the DPRK side of the Korean DMZ a few years back. As you close in on the DMZ the roads get narrower, then narrower, then you start to see brutalist-looking concrete sidewalls, sculptures, & overhead signs all over the place.

We all thought they were sculptures (there's a lot of brutalist concrete in the DPRK). Turns out they're tank traps! You can see a few pics at the top of this article[0], they're pretty neat.

[0]https://99percentinvisible.org/article/hostile-terrain-tank-...

EDIT: Looks like South Korea may have these near the DMZ too!