Standing atop 2nd-century Roman ruins, this church is one of the oldest and most iconic in Old Cairo.

Get up close and personal with these majestic fish.

The air force base preserves its scars from the Japanese attack on Pearl Harbor.

This World War II-era bunker is now packed with posters and props from movies and TV shows filmed nearby.

The grand marquee of this abandoned Hawaiian theater remembers the building's elegant past.

Once the site of the Hawaiian monarchy, this building was originally designed as a palace.

A Hawaiian stairway to heaven—that you can't climb.

More than 2,000 species of tropical plants call this nature preserve and sanctuary home.

A unique set of caves that spits waves back out into the ocean.

This legendary urban waterfall creates a dazzling display of rainbows.

The only royal palace on U.S. soil has been a territorial capitol, a military headquarters, and a prison for a queen.

Doris Duke's lasting collection of Islamic Art, hidden in a Hawaiian paradise.

Watch the newest land on the planet form before your eyes.

This black shoreline is made up of exploded lava particles.

A well-preserved network of cavernous tunnels have spent silent centuries removing Toronto's waste.

Dig for your own trilobites in this goldmine of invertebrates.

This Colorado hiking trail provides a small gold mine of abandoned gold mines.

Ancestral Puebloan ruins, natural arches, and box canyons abound in this seldom-visited corner of Monument Valley Navajo Tribal Park.

A giant 400-acre preserve in North Florida for displaced wolves.

Rare recess caves fill this unbelievably beautiful Ohio park.

Breathtakingly blue walls shimmer inside the "Glacier Behind the Town."

Oregon's unexpected high desert, displaying layers of time in a colorful show.

Where manatees are the snowbird vacationers in these balmy Florida springs.

The scuba diving training facility was named for the steam that rises from the cave's chimney.