While many readers including Allan Cotterill expressed astonishment at the scale of the walls, some of which extend from one horizon to the other, only sprightly septuagenarian Phyl McKey, of Garran, who grew up on ''Clovelly" between Bombala and Nimmitabel, was able to shed some light on the origins of the walls.

"In the late 1800s the cost of wire was so much, that it was cheaper for big stations to build boundary fences and holding pens using a mix of stones and wire," reveals McKey, adding "station managers paid teams of Chinese labourers desperate for work after the gold rush about one hundred Pounds per mile, no matter how many were working on the wall."

Sadly, most of the walls on McKey's beloved Clovelly were pulled down during the rabbit plague of the late 1890s/ early 1900s, but there are still stretches of remaining walls, including at nearby Bungarby.

Although impressed by the magnitude of the stone walls of the monaro, Alan Hume, of Burrill Lake, wonders how many historic stone walls are still standing in the ACT. "I'm aware of the Tuggeranong wall which runs from just behind the leisure centre in Greenway, each side of Athllon Drive over the hill and virtually all the way down to the Murrumbidgee," reports Hume, who asks, "are there others"?

Although not on the same scale as those around Nimmitabel and Bombala, Canberra has a number of stone walls also dating back to the mid – late 1800s which this column has investigated over the past seven years. Here are my Top 3, which unlike the monaro walls are all publically accessible.

Check it out: Located at the Pine Island end of the Pine Island to Kambah Pool walking track in Tuggeranong, as described by Hume this almost 800-metre long dry stone wall runs up the small hill away from the river and turns at right angles towards the Tuggeranong Town Centre, ending just before Anketell Street and Athlon Drive.

Purpose: Built between 1867 and 1875 as a boundary between Andrew Cunningham's 'Tuggranong' (historic spelling) and Fred Campbell's 'Yarralumla' properties. "It was reputedly built by Chinese labourers, after the gold rush at Lambing Flat and beyond, and no doubt helped by locals too, to keep out straying cattle and other stock intermingling between pastoralists' properties," explains historian Rebecca Lamb.

According to Lamb, after rabbits swarmed into the region in the early 1900s, "wire mesh was incorporated at the base of the wall to try to limit their opportunities for breeding sites." There is also a "ditch and bank" extension that is marked by a row of poplar trees adjacent to the Tuggeranong Town centre swimming pool that used to extend all the way to the old.

Check it out: Hidden on Mt Majura's northern slopes is a 300-metre dry stone post and rail fence.

Purpose: According to Jack Palmer, of Watson, "the wall was built in the mid – late 1800s "to separate block 117, Parish of Canberra, and block 200, Parish of Pialligo."

"The wall is well-known to some orienteers and although the posts have survived fires, the wall is gradually becoming smothered with land slip," reveals Palmer.

Whatever the wall's true origins it seems perplexing that given its proximity to the city and location in one of our territory's premier nature parks that there isn't any interpretation signage to explain to users of the park its significance.

Check it out: Hidden among the heavily forested hills above Glendale Crossing in Namadgi National Park this 30-metre long chest-high wall is carefully constructed from stones and links a number of boulders to form a formidable fort.

Purpose: Although Val Jeffery, Tharwa's unofficial mayor and newly-crowned Member of the ACT Legislative Assembly believes "it was part of a boundary fence to keep sheep in a paddock at Gudgenby Station", there are several more fanciful theories bandied around by some long-time locals, including that it was an elaborate bushranger's hideout.

If it was a boundary fence, why was only 30 metres of it made from stone, and why so meticulously constructed? It's a mystery this column has investigated before, but has so far come up empty handed.

Regular readers may recall the akubra-clad McGrath, who goes by the moniker of 'The Dragon Hunter', as the dedicated ecologist who featured in this column back in 2012.

While searching for the Grassland earless dragon (Tympanocryptis pinguicolla), one of Australia's most endangered lizards, McGrath carefully turned and placed back into position just over 68,000 rocks (yes he kept count!) on the monaro.

"Despite the heritage value of the stone walls, the collection of rocks for any purpose is now an illegal practice as it can have detrimental impacts on a diversity of reptiles," points out McGrath.

According to McGrath, the volcanic basalt rocks on the monaro provide important refuges for a number of threatened reptiles "including the grassland earless dragon, the striped legless lizard, the little whip snake and the pink tailed worm lizard."

"These reptiles are all now threatened as a result of habitat loss and modification such as practices like the removal of rocks," laments McGrath, adding "the presence of these reptiles are positive signs for graziers of good land management."

Meanwhile, still on curious reptiles, John Powell recently discovered this "one-headed, two-bodied" Cunningham's skink (Egernia cunninghami) in his garage on his property near Yass.

"It was alive!" exclaims Powell, adding "the skinks [which are often confused with blue-tongued lizards] breed in my garage with warmth from underneath the freezer."

When I first opened an email from Anne Miller, of Deakin, containing this simulacra photo taken near the Dead Horse Gap Trail near Thredbo, I was underwhelmed. Miller claimed the photo featured the profile of a man's head. However, no matter how hard I looked (even squinting my eyes and standing on my head) I just couldn't see it.

Fortuitously just as I was about to despatch it to my 'deleted items', I received a knock at the door. On returning to my office I glanced at the image from afar, and there 'he' was in all his. Glory. Can you see it? If you can't, stand back a few metres from the photo and it will suddenly (and hopefully!) become clear. The head is looking skywards, nose in the middle, forehead at top far left of rocky range and chin at far right.

Incredibly, Miller explains that she didn't notice the 'elder asleep in bogong country', as she has since coined her find, until she was "looking through some photos printed after a walk in the mountains last summer". What a ripper.

Clue: Think twice before drinking any water held in this 'dam'.

Degree of difficulty: Hard.

Last week: Congratulations to Cate Huntington, of Curtin, who was first to correctly identify last week's photo, sent in by G. Boys, of Ainslie, as the Garangula Art Gallery located on Eulie Road, between Jugiong and Harden. "It is an amazing space and there are fabulous pieces of art all over the property," reports Boys, who especially "loves the cows at the gallery entrance."

The triumphant Huntington beat a predicted paucity of other correct readers (well, it was rated as "very hard") to the coveted prize. These included Neil Reid, of Jugiong, who would be disappointed that he didn't capitalise quickly enough on his local knowledge.

Meanwhile a number of eagle-eyed readers, including Thomas Schulze, of Kambah, and Greg Shaw, of Wagga, recognised the close resemblance of the cow sculptures at the entrance of Garangula Gallery to a cow sculpture by John Kelly stuck in a tree at Docklands in Melbourne. "I've finally found the cows' missing brother!" exclaimed Schulze, who even sent a photo of the Melbourne bovine. "The cow's distinctive shape references William Dobell, who served as a 'camouflage' labourer, producing Papier-mâché cows to disguise airfields and fool Japanese pilots during World War II," adds Shaw.

How to enter: Email your guess along with your name and address to timtheyowieman@bigpond.com. The first email sent after 10am, Saturday August 20, 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 Street, Fyshwick. You can see a selection of past columns here.