Once one of the most polluted caves in America, now an environmental success story and a museum dedicated to caves.

Fabulous formations, weird and wonderful wildlife.

A fibreglass sculpture of a whale shark on the grounds of a petrol station.

Quite simply the largest tree in the world (by volume).

The second-largest giant sequoia in the world.

The massive mountain ash that once stood at this site was cut down in an effort to prove that it was, indeed, the tallest of its kind.

This public work of art pays tribute to an early Aboriginal Australian constellation pattern.

This sacred site lives up to its name with its majestic, color-splashed sandstone formations.

Let these towering termite-building structures tell you where to go.

Kakadu National Park is known for its stunning beauty and its rock art, which represents the longest historical records of any continuous civilization on Earth.

Improbably, the largest wildlife refuge in the conterminous 48 states sits just northwest of Las Vegas, Nevada.

This small museum celebrates the history of an Australian town known as the "Gateway to the Goldfields."

A metal skywalk leads to the top of this striking granite outcrop in Porongurup National Park.

The last vestiges of this ship are mostly buried beneath the sand dunes.

A luxurious doomsday bunker hidden beneath an unassuming Las Vegas home offers the best of subterranean suburbia.

No one knows exactly how deep the world’s deepest geothermal hot spring is.

In 1912, this idyllic Alaska landscape was blown apart in the largest volcanic eruption of the 20th century.

The East Village tenement from the cover of Led Zeppelin’s 1975 album has a tea shop on the ground floor.

The lead horse on a Disneyland merry-go-round that is older than the park itself.

One of the oldest carousels in the United States is still running in the coastal village of Watch Hill.

Climb and walk into the crater of one of the youngest volcanoes on Earth.

When it was built in 1929, this historic bridge was the only place to cross the Colorado River for 600 miles.

The evolution of a simple creek cutting its way through an ochre mountain side.

For this chef, an active volcano is his oven.