These picturesque Hawaiian falls are home to a rare species of fish that uses a special sucker to climb up cliffs.

These medieval skyscrapers dominate the skyline of this small Tuscan town.

This historic covered bridge contains a series of macabre paintings that communicate one thing: everyone dies.

Once the tallest building in the world and the site of "the highest dinner ever held in New York" this building now holds the most expensive penthouse in the city.

Steepest flood safety railway in the entire world.

Inspiring Herman Melville and Henry David Thoreau, Mount Greylock in western Massachusetts is the highest point in the state at 3,491 feet above sea level.

An emerald-green grotto just a short trip from Austin.

Holy Grotto of Montserrat Monastery holds one of Europe's mysterious black Madonnas.

An ancient knight and a symbol of the city's freedom.

This historic folk museum celebrates the attention to detail that makes America great.

Cliffs that hold fossils, including the earliest known reptile, dating back more than 300 million years.

The largest tidal whirlpool in the Western Hemisphere.

Every equinox this Maya pyramid puts on a spooky ancient light show.

The ghostly remains of an accidental sea.

A historic bridge with a lovely acoustic anomaly.

A building so large that it has its own weather.

This California eatery has made a name for itself by embracing Asia's rich history of eating bugs.

The century-old bell and clock tower at UC Berkeley is the third-tallest in the world, and has fossils.

A unique underground structure dating back to the 1st century BC.

One of only two commuter aerial tramways in the United States.

Stunning Roman aqueduct used for 1900 years and still standing.

The glowing blue Nymphaeum of Emperor Tiberius.

The largest earthwork effigy in the world.

One of the few remaining ancient aqueducts described by Frontinus as 'the most solemn testimony of the Empire.'