The watery entrance for condemned prisoners heading to the Tower of London is still visible along the Thames.

Six ravens are kept captive (but well-fed) at the Tower of London to prevent the fall of the Crown.

Eighty million natural history specimens call this gargantuan museum home.

Hear the quietest sound from across the dome.

Largest Kauri tree in New Zealand.

Dolphins, ancient clams and hundreds of waterfalls make this one of the world's top tourist destinations.

A perfect turquoise lake colored with glacier dust.

A glacier pocked with ice caves and surrounded by rainforests.

A galaxy of glowworms—larvae of a gnat—hides deep in the belly of these caves.

Major tourist destination known for its bubbling mud-pools and hot thermal springs.

Tubing through a cave lit with glowworms is a magical underground experience.

Some of the clearest water anywhere in the world.

High winds can make this one scary landing.

New Zealand's only running funicular railway.

A monument to a working class martyr.

World War II ended before these tunnels built to protect vital oil from Japanese bombs were ever used.

Bomb tests and sheep ranchers share the world's largest military land base.

Aqua white sand highlighted with fiery red rocks.

This trio of Australian rock spires may have inspired aboriginal legend or just modern tourism.

A massive stairway that almost wasn't leads to one of Australia's most scenic vistas.

One of the oldest theaters in Australia, it's also said to be haunted by a performer who died on stage.

Once housing children next to hardened criminals this historic jail once displayed Ned Kelly's skull until it was stolen.

A simple tribute to the migrant workers who landed here before walking hundreds of miles to Victoria's gold mines.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.