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

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

Puerto Rico's oldest rum producer started its 140-year-old business with "a little barrel."

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

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.

On this Puerto Rican island, many abandoned naval ammunition bunkers sit open while a few have been padlocked by locals as personal storage.

A magnificent waterfall nestled in the heart of the El Yunque National Forest.

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

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

Legend tells how a Spanish soldier disappeared from this isolated sentry box without a trace.

This tiny home was originally a narrow alleyway.

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

This 20th-century mansion plays a key role in one of Puerto Rico's greatest novels.

This community-driven organization uses education and eco-friendly technology to protect the environment.

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

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

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

The bat-covered home of one of the world's most popular brands of rum is located on a tropical Art Deco campus.

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

This chapel on a cliff is renowned for its healing powers and was founded on the site of a supposed divine intervention.

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

This small primate research island is teeming with playing, fighting wild monkeys.

The world's brightest bioluminescent bay.