The curious underground history of keeping Paris clean.

This one has sailed five times as far as Sir Francis Drake's famous ship.

Hollowed out cedar log tubs set in an ancient towering forest.

Macabre headstones carved with winged skulls, dancing skeletons, and pithy reminders of impending death.

The only arched bridge made of stone on the entire Mississippi River.

Secret hideaway for an alternative beach experience.

A roaring, awe-inspiring double cascade of icy water flows through woodland Oregon like something out of a Tolkien novel.

Controversial tribute to the heavyweight champion boxer who grew up in Detroit.

Home of St. Urho, the fictional patron saint of Finland.

Danish tourist destination well known for open stalls where vendors sell marijuana on the street.

World's first "penitentiary," meant to be humane, drove men insane.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

These curious caverns have been home to mushrooms, gangsters, and disco.

Rustic natural hot springs in the deciduous rain forest.

Only hotel where you can legally launder money.

Toxic waste disaster that founded the Superfund program.

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.

Berthed at the Charlestown Navy Yard in Boston, "Old Ironsides" is the oldest commissioned warship still afloat.

This monument on Breed's Hill proves that one of the most famous battles of the Revolutionary War is misnamed.

Art Deco and “Wrenaissance” mash-up, this recently restored royal residence has been home to kings and comes with secret monkey passages included.

A massive sea stack famous for its appearance in The Goonies.

A former waterfront market is now in the center of town due to some interesting Boston engineering.

Brussels' favorite peeing boy has a sister.

Air Force Academy Chapel made of 100 identical tetrahedrons works to inspire those of all religions.