Most powerful transmitter in Germany only broadcasts in the French language.

Now overgrown, these anti-tank barriers from World War II are sometimes called "dragon's teeth."

Live data is transmitted from the Atlantic coast to instantly recreate the ocean waves in this fountain at the NOAA headquarters.

This overlooked street light once served as a KGB dead letter box.

The crumbling remnants of this 19th-century quarantine hospital hint at the touristy island's darker past.

Invading U.S. troops were first seen from this now-abandoned tower, leading to the Spanish-American War.

This small fort played a huge role defending Puerto Rico’s capital city.

This giant bronze image of Christopher Columbus embarked on a voyage of its own.

This former sugarcane transport tunnel is now a portal to a lovely beach.

An enchanting natural wonder in Puerto Rico's Camuy River Park.

Puerto Rico's once thriving oil company is now an abandoned wonderland of rusty steel.

This ''hidden'' 19th-century bridge played a simple, yet important role during the Spanish-American War.

This former railroad bridge was named after the great river that once flowed below it.

This nearly abandoned "company town" is a ghost of Puerto Rico's once-lucrative sugar industry.

Legend has it this historic port was a popular hideout and smuggling spot for pirates.

The highest peak in Puerto Rico is home to a rare fern that can only be found on six trees at its summit.

This bleach-white graveyard overlooking the ocean is accessed through a tunnel.

The location of Puerto Rico's first water bottling plant, thanks to a collaboration between Mother Nature and technology.

Years of neglect and nature took a toll on this 19th-century lighthouse.

This limestone cave offers an incredible view of the Río Grande de Arecibo valley.

This niche museum devoted to ancient religious artifacts is shaped like the very thing it displays.

Rusting, graffiti-covered tanks litter the beach of this island, once used by the U.S. military for target practice.

The world's second largest single-dish radio telescope, once used to contact E.T.

The world's brightest bioluminescent bay.