In British-controlled India, they had a problem with smugglers.
In a manner typical of English gardeners, they solved it with a Shrubbery.
A 3,701km Shrubbery.
With spines.
And Thorns.
And nasty, sharp, sticky-things!
Oddly, the Spanish Inquisition was not involved.
Ni! Peng! Niwom!!!
Was there a brick-lined tunnel going under it so they could reach the Old Forest?
What an eccentric performance.
I wonder if satellite imagery would be able to show the path of the hedge? Or ground-penetrating radar?
Fascinating topic. Thanks for posting, Bosda! 
We need a bi-level effect with a path.
A path! A path!
In a previous home we lived on a street corner, and neighborhood brats (and some adults) found it convenient to cut across our yard to save a few steps. So we erected the Great Hedge of Jackmanii, composed of very prickly and decorative Rosa rugosa.
A vengeful and possibly impaled trespasser attacked part of the Great Hedge with an herbicide, but R. rugosa bounced back.
We don’t have to worry about corner-cutters anymore, but the idea of an impenetrable hedge still has allure. I’ll be planting some of these come spring.