This innocuous-seeming building is actually the remnant of a major wartime brothel.

135 bronze medallions mark a French meridian line which once rivaled the hotshot Greenwich timeline.

Despite being considered a thoroughly American sport, basketball's oldest surviving playing field is found in the basement of a Paris YMCA.

BDSM, 1930s Style.

Remains of Roman amphitheater hidden in a sleepy quarter of Paris.

A series of abstract, silly sculptures represent the works of a great modern classical composer.

Walk through spectacular aisles of hanging meat and wagon wheel–sized cheese at the world's largest wholesale food market.

This life-size replica of the Statue of Liberty's flame is also a tribute to Princess Diana by default.

The water-powered carriages are long gone, but for over a century this funicular railway has been the fastest route to the highest point in Paris.

The history of radiation is on safe display at the foot of a radiation science laboratory.

Indents in the pavement are all that remain from a grisly death machine in Paris.

19th century pendulum and a clock restored by a rogue group of guerilla artists.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

A Pythagorean funhouse that tries, successfully, to prove that math is the coolest thing ever.

A trove of century-old litho stones from the Puck Building's printing days were discovered behind a cellar wall, and are now hanging in the store.

This curved Manhattan building was built to house the opulence of John D. Rockefeller's oil empire.

Built as a gift to the hottest tastemaker of the time, these hidden quarters remain an Art Deco showpiece.

Long the exclusive domain of birds and vagabonds, this little-known Central Park peninsula is open to the public once more.

The walls are decorated with whimsical murals painted by the creator of the Madeline franchise.

The "Seinfeld" diner.

These giant volcano sponges in Antarctica are thought to be the world's oldest living animal, at 15,000 years old.

Antarctica's bustling metropolis, originally established by Richard E. Byrd.

Fire meets ice at the southernmost volcano on Earth.