The longest fence in the world protects one from the other part of Australia in which they live dog Dingo. Its total length is 5614 kilometers.
This fence, according to different versions, or 500 meters shorter than the Great Wall of China, or 1,500 kilometers long. Depends on how you count the length of Great Wall of China.
Dingo in Australia is also not local - they probably brought immigrants from Southeast Asia about 2500 years ago. And protect them from the Australians local fauna, and their flocks of sheep. Dingoes are very fond of mutton.
Here, on the map marked with brown areas of distribution purebred dingoes, and purple line - the same fence:
Dingo fence for almost do not go. That is, they are trying to go, of course, but protivodingovy fence as protivokrolichy actively patrolled. Patrol monitor the state of the fence and kill all encountered dingo. Here the fence:
Maintaining this nondescript mesh in order costing contiguous with her Australian states, if not lie, 15 million Australian dollars a year. Well, that - the longest fence in the world after all.