An enormous concrete structure built over a nuclear crater.

The birthplace of both the Atomic Age and Godzilla, and the namesake of the bathing suit.

Dublin's "Dead Zoo" serves as a window to Victorian museum design.

The oldest public library in Ireland.

The mummified heart of a saint lives on in this church—after a brief hiatus when it was stolen.

The world's most remote permanent settlement on an active volcano.

Mother Nature outdoes herself with this stunningly beautiful set of caves carved into marble.

Hundreds of prehistoric stones, arranged in perfect lines in a French field.

Human-made caves excavated to hide a secret society of wealthy pagans.

An 18th century monument regularly tagged with unsettling graffiti referencing a 1940s unsolved murder.

One of the greatest maze designer’s greatest mazes.

When the rain falls, this drain system turns into a musical instrument.

An ancient hotspot for spotting schools of fish.

A mysterious ancient cemetery with Roman sarcophagi and Lycian inscriptions.

Nightmarish example of the unintended consequences of weapons testing.

Finnish lake, and scene of an infamous murder mystery.

Sweden's first nuclear reactor, R1, can be visited 25 meters underground.

An abstract monument to a symphonic composer.

This hospital fell into ruins after failing to act as the advocate for the mentally ill it was designed to be.

Space-age monument to an early 20th-century uprising.

Dictionary Johnson’s favorite feline.

This stunning, out-of-the-way Croatian monument commemorates a community's uprising against occupying fascist forces.

This lonely cast-iron structure is the only wave-washed lighthouse of its kind left in all of Britain.

The hallucinogenic center of the ancient world.