"If you think this is good," they said when I visited Ayers Rock, "just wait till you see the Bungle Bungle."

I was puzzled. I hadn't the slightest idea where I might find a Bungle Bungle, or even exactly what one was.

But now I know, and they were right. The Bungle Bungle is amazing.

Put simply, the Bungle Bungle is a sandstone massif in the Kimberley region of north-western Australia that has eroded into strange and beautiful rock formations. Now, I've seen a lot of rock formations. Some you get excited about and some you don't, but the Bungle Bungle is definitely worth getting excited about. This is natural rock sculpture on a monumental scale - 280 square miles of it - and so extravagantly spectacular that it leaves visitors speechless.

The approach road, a sandy 4WD (four-wheel drive) track, runs beneath sandstone cliffs that form the western face of the massif. We drive through surprisingly green woodland full of Australia's unique flora - slender silver-trunked gum trees and bloodwood trees that ooze red sap; termite mounds twice the height of a man; yellow wattle bushes and purple mulla- mulla wildflowers. Emus glide through the bush and frilly-necked lizards bake in the sun. Wedge-tailed eagles soar overhead. The car slides a little in the sand, then tilts alarmingly as we lurch into and across a stony dry creek.

None of this prepares you for what awaits as you round the southern tip of this western flank. The track curves back and suddenly, above the trees, appears one of nature's marvels - a sight to compare, say, to the Grand Canyon or, indeed, to Ayers Rock. A solid wall of thousands of massive rock domes, stacked above one another like a giant crowd on a football terrace. These "beehives" stretch as far as you can see, their striking orange and black bands shining in the fierce sunlight. It's unlike anything else on earth.

Close up, the domes tower over us, as large as cathedrals, like the ruins of a mysterious ancient city. It's possible to hike up the creek bed of the main gorge, Piccaninny Creek, deep into the heart of the massif, a breathtaking 11-mile return journey through the domes that takes two days. A shorter walk, popular with tour groups (and most visitors come on tours) leads to the half-covered orange rock amphitheatre of Cathedral Gorge.

The Bungle Bungle is the remnant of a 360 million-year-old block of sandstone, over 600 feet high and 16 miles or so along each side. (The circumference of Ayers Rock is five-and-a-half miles.) Seen from the air, the top of the massif is a broken plateau, flat bushland with small waterholes that support a few wallabies and other wildlife. The north and west walls are sheer cliffs, absurdly orange, riven with narrow chasms and gorges that shelter tropical palms, while along the southern flank lie the tiger-striped beehives.

These were formed by familiar forces: wind and water eroding the soft sandstone. The striped effect is a little more involved, but what's really amazing is that such dramatic and complex results derive from just a few basic rules; that such strange beauty should be merely the unplanned side- effect of water trickling into a crack. It's all... well, unnecessary. Why should the outcome of such simple, relentless processes be so fantastic, so bizarre? It's as if God had some spare rock left over from creating the world and decided to mess around and do something really weird, just (to use a slightly inappropriate phrase) for the hell of it.

Until recently, this unique natural wonder had only been seen by a handful of settlers and Aboriginals. The name "Bungle Bungle" is probably a corruption of the Aboriginal word purnululu, meaning sandstone, which is now the official name. (An alternative explanation is that it's a mispronunciation of "Bundle Bundle", a local species of grass.) Then, in 1982, an Australian TV crew got wind of its existence and the resulting documentary launched it on to the tourist map.

If it's surprising that something as spectacular as the Bungle Bungle could escape almost unnoticed for so long, then bear in mind that the Kimberley, often dubbed "Australia's last frontier", is three times the size of England, with one sealed highway and a population of only 23,000. The first white settlers only arrived in the 1880s. This semi-tropical wilderness, as remote from Sydney as Moscow is from London, is rich in magnificent scenery, rugged ranges, dramatic gorges and untouched coastline. Remember, too, that Ayers Rock itself (now officially called Uluru, incidentally) was almost unknown until the 1960s - and now half-a-million or so people each year travel 1,240 miles into the middle of nowhere to see it.

So is it better than Ayers Rock/Uluru?

While there's an obvious superficial similarity (ie, they're both big, orange and made of rock), the comparison is ultimately futile. If Ayers Rock is a haku - a single point punctuating a vast plain, compelling for its stark simplicity - then the much larger Bungle Bungle is a sprawling Dickensian epic that overwhelms you with sheer scale and sustained virtuosity.

Watching Ayers Rock change colour in the fading sunlight, you feel like a mere worshipper at a shrine. Standing in front of Purnululu's mighty walls, you are simply slack-jawed in astonishment.