1. Natural Bridge, Qld

Location: Springbrook National Park, Qld
The Natural Bridge is an area where rainforest springs and short tributary creeks form the headwaters of the Nerang River. Through the process of time a deep cave formed behind a waterfall on Cave Creek. Upstream of the falls, a  pool was scoured by tumbling water and rocks until the waters partially broke through the basalt rock of the creek bed to flow into the large cave below. This diversion of the stream created a perfect arch or bridge in the rock above. A waterfall plunges through the roof of a cave into a beautiful sun-dappled rainforest grotto, which is home to glow-worms, bats and other denizens of the dark.

Location: Jenolan Caves, Blue Mtns, NSW
What is often missed by visitors to Jenolan Caves is the huge Grand Arch that all vehicles must pass through on their way to the main carpark. The arch was once the entrance to a large limestone cavern now occupied by the carpark, Caves House and visitor facilities. Due to water seepage, the cave collapsed many centuries ago, but the arch remain. At 24 metres high, 55 metres wide and 127 metres long, the Grand Arch is the largest open cave in Australia.

3. Carlotta Arch, NSW

Location: Jenolan Caves, Blue Mtns, NSW
Another large cave remnant at Jenolan Caves, Carlotta Arch is like a huge window looking out high above the Devils Coach House. The arch is one of the most photogenic natural arches in Australia, though because of its sheer size, it is difficult to capture its majesty and grandeur accurately in a photograph. A hiking trail climbs up to and behind the arch, allowing photography from both sides. This trail then proceeds to and through The Devil's Coach House. Carlotta Arch has a span of about 20 meters. A viewing platform under the arch offers views to Blue Lake.

Location: Queanbeyan, NSW
A natural limestone bridge to the south of Queanbeyan, it was formed when sediment and corals remains were deposited on an ocean floor 420 million years ago. It was then subjected to intense pressure. Over time the ocean receded and erosion shaped the landscape. The arch was formed by water slowly leaching through the limestone, enlarging cracks until a passage became big enough for Burra Creek to pass through. It reached its present size about 20,000 years ago.

Location: Budawang Ranges, Moreton NP, NSW
Corang Arch is found on the western side of the northernmost tip of Corang Plateau in the Budawang Ranges of southern NSW. An impressive bit of erosion, the arch is much larger than photos indicate. Many more arches are forming in the cliffs of this large sandstone spur, but none will rival the height and size of Corang Arch. It is easily found if walking close to the cliff edge. Access is through a small cave (forming another smaller arch) in the rock platform at the cliff edge.

Location: Litchfield National Park, NT
The arch is situated in the upper reaches of Tolmer Gorge just above Tolmer Falls. A little further upstream, Tolmer Creek passes through a steep gully before dropping into and flowing through a deep circular cavern known as The Cauldron. The arch can be reached by a bushwalking trail which leads from the arch lookout back to the carpark via the broken sandstone rim of the gorge. Tolmer Falls is one of three major waterfalls along the western face of the tabletop range. The caves in the gorge below Tolmer Falls are home to a colony of the rare Orange Horseshoe Bat.

Location: Kakadu National Park, NT
Known simply as The Archway, this natural arch near the border of Kakadu National Park dramatically illustrates the erosion that has carved out the many rock features of the Arnhem Land sandstone plateau. It is the largest of hundreds of arches and caverns scattered throughout this ancient countryside. Being on Arnhem Aboriginal tribal land, it is not accessible to the public by land. The only way to see is by taking a helicopter or airplane trip out of Jabiru Airport in Kakadu National Park.

Location: Kalbarri National Park, Kalbarri, WA
The river gorges in the Kalbarri National Park are some of the most accessible and spectacular in Western Australia. These gorges were carved over millions of years to form dramatic sandstone cliff faces that plummet into the Murchison River as it meanders towards the township of Kalbarri on the coast. Short walks provide moderately easy access to lookouts along the river gorge at the Loop, Z-Bend, Hawks Head and Ross Graham lookout. The Loop provides different views of the winding gorge below from several lookouts positioned around The Loop. One such vantage point is Nature's Window, a natural rock arch that superbly frames the upstream view.

Location: Sandstone, WA
Up a track from the State Battery near the goldmining ghost town of Sandstone is the region's most interesting natural phenomenon - London Bridge. It is the most spectacular and unusual of the sandstone breakaways in the area and, in the early 1900s, was once wide enough to allow both horse and sulky to cross it. Over the years however, it has been eroded to its present width of one metre. It is now regarded as too dangerous to walk on. The sandstone in this area is estimated to be 350 million years old. The bridge itself is nearly 800 metres long and at the centre is 10 metres high.

10. Undara Lava Bridge, Qld

Location: Undara Lava Tubes, Undara, Qld
The main attraction of Undara National Park, a few hundred km southwest of Cairns, are its lava tubes. They are the largest, longest and most accessible lava tubes on earth. The Undara volcano erupted 190,000 years ago and spewed 23 cubic kilometres of molten lava onto the surrounding country. Streams of sulphurous lava flowed over the land, spilling out like boiling treacle into various creek beds and other depressions. The surface soon cooled and crusted but the molten lava inside continued to flow, leaving behind these huge hollow pipes. The large bridge at Undara was caused by the collapse of one of the tubes. It has a span of 20 metres and a height of 11 metres.