Spreading out like a giant spider web, extending to the horizon in every direction are the striking ruins of an extensive array of dry stone walls.

The vista of the walled-landscape from atop this windswept hummock between Nimmitabel and Bombala is truly remarkable. Remarkable in that despite their extraordinary length (estimated at more than 200 kilometres in total), hidden behind hills from the busy Monaro Highway, and only accessible from a handful of private grazing properties, the very existence of these walls has remained a secret to many for so long.

"Little has ever been documented and few people have ever seen them," remarks grazier Howard Charles of 'Rockybah', who along with neighbouring farmer Henry Bridgewater of 'Sherwood' own properties, which due to the walls, more resembles farmland you'd expect to see in the Cotswolds of England and not southern New South Wales.

Joining my wall fact-finding mission are Claudia and Alastair, Bridgewater's two akubra-clad children and Barry McGowan, a Canberra-based historian and heritage consultant.

While the field trip is just another chance for Claudia and Alastair to test out their balancing skills on the wobbly walls, which stretch from one end of their farm to the other, for McGowan who has studied stone walls along the east coast of Australia for several decades, it's a real eye opener.

"These are seriously impressive," he says, standing atop the hill, mouth agape, in awe at their extent.

"It's incredible, they are straight for as far as the eye can see," points out McGowan. "What wonderful survey work."

"As a crow flies that's over 20 kilometres," adds Charles pointing towards the Great Diving Range on the eastern horizon.

So who built them and why are they now in ruin?

First to their origins, on which there is more folklore than detailed documentation.

A visit earlier in the day to the Federal Hotel in Nimmitabel revealed that, according to local lore, the walls were erected by Pacific Islanders kidnapped by the exploitive Ben Boyd in the 1840s (yes, of south coast fame) to work the vast swaths of land stretching from Eden on the far south coast through to the high country.

However, McGowan isn't a subscriber to the Pacific Islander theory. "While Boyd did recruit some Pacific Islanders in the late 1840s to work as shepherds it is very doubtful they built these walls," says McGowan, explaining "they would not have had the skills, organisation or numbers, and in any event were not around for that long, most of them absconding as soon as they could".

Imagine being plucked from basking in the tropical paradise of your homeland only to be tasked with manual labour on the bitterly cold Monaro, which only years before was "beyond the limits of civilisation"? Heck, I'd run too.

Instead, McGowan, who is also an honorary senior lecturer at the Australian National University's College of Asia and the Pacific, believes "the walls have all the characteristics of careful, meticulous work associated with large gangs of Chinese labourers on the goldfields and elsewhere".

"The most likely scenario is that the labour was recruited from the local 'Chinatown' at Craigie located near Bombala," says McGowan, who has uncovered evidence of "similar systems in which Chinese labour was recruited from the Chinese camps in Riverina towns, such as Narrandera, Wagga and Albury to undertake land clearing".

"Building such an extensive system of walls would have required large gangs of labour," says McGowan. "Local labour in these quantities would only have been available from Craigie".

There are other pieces of evidence that support McGowan's theory including the remnants of Chinese market gardens complete with artefacts on the river flats of Rockybah and a local farmer whose grandfather's diary makes note in the 1860s of paying the Chinese "two shillings a chain to build walls".

Further supporting McGowan's theory are anecdotal reports from "old timers" passed on to Charles that "the head honcho in charge of the Chinese workers would ride around with his leggings and cracking a whip to make sure that everyone kept up the hard work to the job".

It would have been back-breaking work hauling the rocks from the far reaches of the property and then expertly constructing kilometres of walls.

So why are so many of the walls now in ruins? Are they simply victims of the vestiges of time?

Not at all. "They were built too well for that," Charles says. "They'd still be standing proudly now if it wasn't for the rabbit plagues of the 1890s."

And he's right. Local histories record that in an attempt to reduce the number of rabbits, which were decimating the grazing land already under stress from drought, landholders on the Monaro were ordered to dismantle the stone walls, among which many rabbits were breeding.

"The property boundaries were extended a chain width as compensation for the work to rip down all the walls," explains Charles, pointing to the modern fence lines that run about 20 metres away from the stone walls.

Just imagine how the Chinese workers, who meticulously toiled away to build the walls, must have felt if they discovered that only a couple of decades later, the fruits of their labour were unceremoniously demolished.

There is still much to uncover about the walls and both Charles and Bridgewater would love to hear from anyone who has further information on their origins.

"They are a forgotten chapter in Monaro's history," Charles says. "It's a history that needs to be unearthed and told."

One thing is for certain: McGowan is impressed just by their presence, for at the end of a long day following them up hill and down dale, he is still shaking his head in disbelief at their extraordinary extent.

Boundary fences aren't the only stone structures dating from the 1800s that are still standing in the Monaro.

Pre-dating the walls are a number of folds, an ancient style of rectangular enclosure built by shepherds to protect their flocks at night.

In other parts of Australia, similar enclosures were built in the early 1800s with timber, but as the Monaro was naturally devoid of any timber, the area's first shepherds turned to stones instead.

With most thought to have been built in the 1830s-50s, folds in the Monaro were built near fresh water and just below the top of hills enabling the sheep to be sheltered from the prevailing wind. They vary in size, with some only able to hold 200 sheep and larger ones able to hold a couple of thousand head.

Following the advent of legislation that improved land tenure along with the availability of fencing wire, from the late 1800s wire paddock fences like the ones on farms today replaced folds to control stock movements and grazing.

Unfortunately, just like the dry stone walls, all the folds I am aware of on the Monaro are concealed on private property and not publicly accessible.

Did you know? In biblical times, John the Baptist told how shepherds would lie across the entrance to keep the wolves out, and that anyone who entered in another way was considered a thief and a robber.

Cryptic Clue: Bronze.

Degree of difficulty: Medium-Hard

Last week: Congratulations to Kate Howarth of Bega who was first to correctly identify last week's photo as the Thredbo Ski Museum. The museum is open daily (except Mondays) from 1pm-5pm over winter and boasts a comprehensive collection of winter sports memorabilia. Entry is free.

How to enter: Email your guess along with your name and address to timtheyowieman@bigpond.com. The first email sent after 10am, Saturday, July 9, 2016 with the correct answer wins a double pass to Dendy cinemas.

CONTACT TIM: Email: timtheyowieman@bigpond.com or Twitter: @TimYowie or write c/- The Canberra Times, 9 Pirie St, Fyshwick. You can see a selection of past columns at: canberratimes.com.au/act-news/by/Tim-the-Yowie-Man-hvf8o