"Notan" wrote in message
Built properly, a concrete wall can stop just about anything.
Think: Hoover Dam.

Constant, evenly dispersed pressure.

How long will it take a backhoe to get through it?



A backhoe is a lightweight device, all things considered.

Not.

Relative to what? There are many mechanical or structurally made 10 x or
more heavier than even a big backhoe.