Now abandoned, the first public health hospital in the U.S. saw more than one million immigrants from around the world.

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

The world's brightest bioluminescent bay.

Meet manatees face-to-face at this zoo for native species.

A book bound in the skin of an infamous criminal, along with countless other specimens.

Romania's triumphal arch looks out over Bucharest.

This communist behemoth is the heaviest building in the world and a legacy of a brutal regime.

This memorial to the victims of the Romanian Revolution of 1989 is often compared to a potato on a skewer.

A medieval church built up to defend its village.

The European towns of Brașov and Râșnov each have proud signs reminiscent of the Hollywood sign.

A fire once nearly devoured this gorgeous 14th-century Gothic cathedral.

This once-derelict building is now one of the most beautiful bookstores in the world.

The possible imprisonment of Vlad the Impaler here earned the medieval castle its nickname, "Dracula's Castle."

Nine centuries-old fortresses guard the walls of this medieval Romanian city.

This massive underground salt mine now holds a sci-fi theme park in its depths.

This Transylvanian church has changed its denomination four times.

Some call this eerie forest of crooked trees the "Bermuda Triangle of Romania."

Fascinating museum dedicated to the under-appreciated medical history of urology features some wince-inducing devices.

This functioning mill was built in the 1970s using parts from several other West Virginia mills.

A century-old cabin off of Highway 30 touts an unusual construction material: dinosaur bones.

An organ located deep within a cave, whose "pipes" are the geological features of the cave itself.

This abandoned amusement park was built on a site with a dark history.

America's post-nuclear-attack chambers of Congress.

Millions of years of oxidation make a drive down this winding Death Valley road surprisingly colorful.