"Where the ducks walk on fish."

Beside a busy highway, a colony of Great Blue Herons raises hundreds of offspring each year.

These "bridges" help confused bats cross the road.

This Roman quarry once held secret masses and smuggler's contraband and is now home to rare species of bats.

A massive cave once a secret military base is now home to thousands of bats.

These former Nazi anti-aircraft towers offer a singular view of the north of Berlin in the summer, and a sanctuary for bats in winter.

What was once an underground Nazi city is now Europe's largest bat reserve.

Man-made mineral caves house massive bat colony.

A giant Australian fruit and tropical farm.

This abandoned railroad tunnel is now home to a micro-colony of bats and a ghost train.

One of the oldest restaurants in the Seychelles.

Nearly 40 miles and 1,000 years of limestone mines under Denmark.

Wondrous stalactites house thousands of bats in these African caves.

Zambia's smallest national park is home to one of the world's largest annual mammal migrations.

This cavernous swimming spot doubles as a home to the largest known colony of bats in Central Asia.

Thousands of bats stream out of caves every night on the edge on Thailand's second largest park.

An immense cave that has served as an outlaw's treasure trove, an underground dance hall, a nuclear fallout shelter, and much more.

The world's largest occupied bat houses hold hundreds of thousands of flying mammals.

This three-chambered cave is the only protected natural bat hibernaculum in Quebec.

Nondescript building owned by ExxonMobil working on siphoning Greenpoint Oil Spill out of the ground.

An unfinished rail tunnel that has since been used to house cheese and bats.

Thriving meadows span a rooftop in one of Brooklyn's most heavily industrialized neighborhoods.

This large cave is a summer home to thousands of bats and has a rich history dating back to prehistoric times.

These otherworldly caverns form Earth's oldest known cave system.