Oodnadatta Track, South Australia: The worlds largest art installation

Marree serves tourists and station owners, but when I arrive, the summer heat shimmers and the windows are pulled shut in a High Noon sort of way. At the heart of the town is a defunct railway station with two derelict Ghan trains waiting patiently. These bullish old locos are the colour of dried blood and have an inverted chevron on the nose. One has a sign: "FOR SALE". Oddly enough, they're rather lovely.

In the 1970s, the old Ghan line – tormented by flash floods for 90 years – was moved 200 kilometres west. Railwaymen and their families moved out, and people with things to do other than marshal locos or muster cattle moved in.

One of them was Bardius Goldberg, an itinerant artist with a need to express himself in a big way. In the mid-90s, it's widely believed he used a tractor and plough to carve a four-kilometre figure on top of a remote plateau. Working alone and at a modest elevation, Goldberg's ploughing went unnoticed as he formed a beautifully proportioned figure of an Aboriginal man. His work was happened upon by a pilot in 1998, some years after its creation and there was much speculation as to who was behind it. Aliens and US intelligence were among those named.

"Marree Man was said to be the world's largest piece of art," says publican Phil Turner. "It's certainly the world's largest geoglyph. It was made back before everyone had GPSs so people were amazed it could be done so precisely. I suppose that's where all the talk of aliens came from."

Phil's pub is the two-storey Marree Hotel. Its chimney is painted the colours of Port Adelaide, a team based on gulf waters 700 kilometres away. "There's talk of the figure being redone," he says. "The Arabana people are very keen to preserve the myth and the mystery – they can see some benefits flowing back to the community. But at the moment you can only just see the outline using Google Earth."

Actually, you can't. Most of Goldberg's 20-year-old plough-strokes have disappeared, rubbed out by erosion and saltbush. The artist too has gone, said to have died from septicaemia in 2001. Apparently, he got into a fight, broke a tooth and refused to get treatment.

I drive 60 kilometres west to visit, but the plateau is on private land so I can only admire its exposed parched plains – a drizzled pallet of cream, apricot and peach.

Other artists have chosen to execute huge pieces of work in the same desert void. Not far from the Marree Man canvas is the Mutoid Waste Company's post-apocalyptic sculpture park. "Park" is perhaps over-egging what's basically a few aces of scrub, but it's famous for "Plane Henge", two Cessnas standing Christ-like on their tails touching wingtip to wingtip.

They're fabulous when viewed on the biblical horizons of the Oodnadatta Track, but just as good up close. "Conceived and raised by Mutoid Waste Company to mark the passage of the Earth Dream Journey 28 May 2000" reads an inscription. The fuselages are painted with quasi-indigenous earth spirits – quite serene against the acid blue of the sky. Galahs have nested in the nose of one of the aircraft, small, noisy splashes of pink.

Mechanic Robin "Mutoid" Cooke added a new sculpture to his park each year, transforming materials that would not rot away. Today, gleeful giants fashioned from steel rails and engine blocks dance under the sun. There's a steel tree of knowledge and a xylophone fashioned from hub caps invites travellers to make desert music.

All of it has been dubbed – rather brilliantly – "recycladelic".

I drive 150 kilometres more, past the headache-inducing expanses of Lake Eyre, past stone ruins of railway fettlers that have been brutalised by the heat, to a piece of outback art in more comfortable surrounds. The hotel in the town of William Creek (population five) has been a work in progress for decades, its sensible walls and ceiling steadily filling with graffiti, flags, business cards, hats, expired licences, foreign currency and underwear.

This is another outback artform that could benefit from a name, transforming far-flung bar-rooms into extraordinary spaces of texture, line and colour. In centuries past, travellers added rocks to lonely cairns, acknowledging their passage but also leaving a beacon for future safe passage; today, shearers, miners, soldiers and backpackers leave their own form of reassurance in these lonely outposts: "good times had here".

I enter the bar to encounter a friendly German girl, the only face in town. I'm shocked. Some of the walls have been painted over, the precious graffiti vandalised. The ceiling, previously groaning with travellers' mementoes, including the largest bra I've ever seen, has been viciously pruned back.

The barmaid tells me the new owners "needed to clean up" for safety reasons. In protest, I decide to take my custom to Oodnadatta, 200 kilometres up the road. Though not before buying a cold beer. And $100 worth of diesel.

It's getting late so I hunch over the steering wheel and push into the hot plains of "gibber". The blackened stones gleam like they're wet; great vales of nothing run out to low ranges rounded by millennia into sulky forms of grey, yellow and olive drab.

A little way out of town I see a road sign. It's painted pink – a poorly-made, cartoonish thing indicating food and comforts to be had at the "Pink Roadhouse" in Oodnadatta. I think nothing more of it, until I see another, hand-painted with dense text, staked into the ground beside a vantage point.

After 50 kilometres and the fifth such sign, I pull over. The distinctive hand-written sign is warm and human, cheerfully talking to "you" the reader, unafraid of exclamation mark.

The signs are dedicated to the precious land corridor that is the Oodnadatta Track – a lifeline between the deadly salt lakes, a place where secret waters bubble out of weird mound springs in the desert. They tell how Aboriginal peoples regularly used it to carry the sacred ochre from the Flinders Ranges – the world's oldest trade route. How British explorers solved the riddle of the hitherto forbidden Australian interior, finding the corridor in the 1840s. How cattlemen pushed into the 'void' to fence land and secure vital waters. How telegraph poles carried the singing wires to the Timor Sea. And how the narrow gauge railway line carried the earliest Ghan trains from Marree to Oodnadatta and eventually to Alice Springs.

Small contemporary stories are told, too. 'The wreck of Fred's car is still beside the railway bridge – he lived to tell!' Travellers are encouraged to connect, have fun, show respect and stay safe. 'Be careful' says one before a lonely dirt track, 'it's remote out there!'

As I drive, I become convinced of the signs' beauty. Kooky and innocent, they're reminiscent of the work of Ian Abdullah and Reg Mombasa – and I'm sad to see many are fading. I begin to view them as a European songline, stories written into the scrolling landscape telling of landform, legacy and ancestors.

As I arrive in Oodnadatta with a low sun at my back, I realise them for what they are: a vast piece of art.

The Pink Roadhouse is exactly as advertised, a place for people with tents, caravans and need for a bed. It's also very pink. There are pink seats, pink bins, a pink Volvo. The owners, Neville and Adriana Jacob, bought the roadhouse two years ago.

"Have you ever considered you might have the world's largest art installation?" I ask. "Apparently the signs run for at least 400 kilometres."

"No, I haven't thought about it like that," says Adriana. "But we're wanting to have them redone because the weather is starting to get to them. They are beautiful. Apparently, Adam loved it here. He never wanted to go."

Adam Plate, who "put the signs all over", was a motor racing fan. In 2012, he took part in the Targa Rally, a fast, hard race through Adelaide Hills. When his Lancer EVO hit a tree he was killed.

All of the art I've encountered on the Oodnadatta Track has seen the artists use something in addition to their pink paint, their plough share and their arc welder. And that's isolation – the extraordinary isolation this continent has in abundance. Art needs people as surely as the falling tree needs someone to hear its falling. But to be the only person communing with another's creativity within a landscape of solace is special indeed. It's the feeling of being incredibly connected to other people – paradoxically while being the sum total of one.

See also: Nine awesome tourist attractions in odd places

TRIP NOTES

MORE INFORMATION

southaustralia.com/

STAYING THERE

The Marree Hotel (see marreehotel.com.au) has double rooms above the friendly pub from $120 a night; it also has the (rare) luxury of a pool. The William Creek Hotel (see williamcreekhotel.net.au/) has double suites from $90. The Pink Roadhouse (see pinkroadhouse.com.au/) has a range of accommodation; en suite cabins from $120 per night. All offer camping options and a restaurant.

GETTING THERE

All major airlines operate frequent flights between Sydney and Melbourne to Adelaide. See qantas.com.au; virginaustralia.com; jetstar.com; tigerair.com

Adelaide Airport is home to most hire car companies. If you want to do the camping thing, Britz (see britz.com.au) hires fully equipped 4WDs from around $60 a day. The Oodnadatta Track is well-maintained and virtually flat so you don't need a 4WD. But you do need to be sensible about your speed. You also need to carry provisions, most critically water. If you continue north past Oodnadatta for another 200 kilometres, you reach the Stuart Highway for smooth driving all the way back to Adelaide.

WHAT NOT TO MISS ON THE OODNADATTA TRACK

THE REPLICA MOSQUE IN MARREE The original mosque – basically a group of tree stumps topped with thatch facing Mecca – was Australia's first, built by cameleers in 1861. Though called "Afghans", these men were from provinces of modern-day Pakistan and basically kept the desert supply-lines open. The reconstructed "bough shed" mosque is in the centre of town.

THE MOUND SPRINGS Don't miss them. Rising like igloos from the plains (and about as incongruous) they leak two-million-year-old water from their peaks, forming impossibly green micro-wetlands. The most accessible mounds (including 'The Bubbler and 'Blanche's Cup') are 20 kilometres from Coward Springs.

COWARD SPRINGS The perfect place to take a break or camp overnight. Enjoy a dip (and a beer) in this "natural spa" of mineral waters; then check out the old railway siding and birdlife in the thick wetland reeds. Magical.

WILLIAM CREEK This tiny outpost is home to the eponymous pub (already regenerating itself courtesy of enthusiastic patrons) as well as Wrights Air (see wrightsair.com.au/), your ticket to get a birds-eye view of Lake Eyre and deserts.

THE OLD GHAN The dirt road pretty much follows the Old Ghan line – now a narrow relic of earth and rotted sleepers. Look out for messages formed by sleepers arranged to form huge letters in the dirt.

THE ALGEBUCKINA BRIDGE a beautiful piece of late-Victorian railway infrastructure. It crosses one of few permanent bodies of water.

THE OODNADATTA MUSEUM in the old railway station A rich repository relating to outback life. Take your time and check out the poems by kids living on remote stations. Some of them are surprisingly powerful.

THE TRANNY The Transcontinental Pub in Oodnadatta is owned by the local Aboriginal people and a cool place to meet locals. Manager Brad is a really nice guy.