The Dingo Fence (or Dog Fence) is the longest fence in the world, stretching 5,614 kilometres (3,488 miles).

Dingo Fence (©paula mcmanus)
The fence was built in the 1880s to keep dingoes out of the prime farming and sheep grazing lands in the south eastern section of Australia. It worked and still continues to be successful today, although some dingoes do get through due to holes and other fence break downs, but the losses have been considerably reduced.
The dingo is a wild dog and is the largest terrestrial predator in Australia. Livestock farmers see the dingo as a pest and despite it being an apex predator, the dingo species is listed as vulnerable to extinction - mostly due to genetic pollution (ie cross breeding) which is diluting the dingo's unique characteristics.

captive dingo (©paula mcmanus)
Australian sheep and cattle stations are large - some are larger than whole European countries. After a station lost 11,000 sheep in 1 year due to dingo attacks, the farmers tried many methods to keep the dingoes away from their sheep stocks. They laid poison baits and shot dingoes on sight, but eventually they had the fence built.
The dingo fence originally started as a rabbit proof fence. Rabbits were introduced into Australia and quickly became a real threat to farm lands. Unfortunately the rabbit proof fence was unsuccessful in keeping the rabbits out, so plans were made to add to the fence height and keep the dingoes out. For the most part, it has worked.

Dingo Distribution by Inugami-bargho (see footnote)
The construction of the fence took approximately 5 years. The fence was built in some of the most remote and harsh outback areas in the country. It starts in Jimbour on the Darling Downs in Queensland and ends just above the Great Australian Bight on the Nullarbor Plain in South Australia.
There are more than 20 Wild Dog Barrier Fence staff who patrol a distance of 300 kilometres in 2 person teams each week in order to maintain the fence.
Mostly, the fence is wire mesh, but there are some sections in South Australia that are multi-strand electric wire. The fence is generally 180cm (5ft9in) high.

Dingo Fence (©paula mcmanus)
Large numbers of dingoes still exist on the other side of the dingo fence. The fence is a testament to those early landholders who fought (and still fight) hard to protect Australia's multi-million dollar sheep industry.
I stood at the Dingo Fence just outside of Coober Pedy in South Australia. The South Australian section of the fence is 2,250 kilometres long. I found it quite a surreal moment to be standing alongside one of the worlds longest structures and an Australian history icon.

Dingo Fence (©paula mcmanus)
Postscript: Map of Dingo Distribution - drawn after a map in A MANAGEMENT PROGRAM FOR THE DINGO (Canis lupus dingo) IN THE NORD-TERRITORIUM OF AUSTRALIA; AUSTRALIA 2006-2011 PARKS AND WILDLIFE SERVICE DEPARTMENT OF NATUAL RESOURCES, ENVIRONMENT AND THE ARTS, page 4. Licensed under CC BY-SA 3.0 via Commons)