The former Nazi concentration camp stands as a museum to remember this dark chapter in European history.

Houses are tucked between, on, and underneath giant boulders.

The world’s narrowest house makes for an awkward, four-foot-wide living space.

A national collection of Communist-era musical posters.

A tribute to the Polish insurgents who fought in the failed attempt to end their city's Nazi occupation.

A hidden art gallery in an abandoned Warsaw fort.

This futuristic German spa allows visitors to float in a pool of salt water while zoning out to underwater techno.

Its front wall is striped with a menagerie of fantastic beasts and magnificent monsters.

Why walk on this historical site when you can zoom down instead?

A domed disco abandoned since the '70s now attracts artists and explorers under its unique roof.

Genesis of modern hydroelectric power.

One of many reminders of Tesla's scientific contributions overlooks the falls which inspired him.

A sobering museum dedicated to landmines and the personnel working to remove them from Afghanistan.

A little marble compass above George Washington's (empty) tomb in the Capitol marks where D.C.'s four quadrants intersect.

Mirrored floors and arched shelves create the illusion of an infinite tunnel of books.

A complex, nine-layer maze on the grounds of a Venetian doge's playground.

The museum calls itself the "National Museum of the Paranormal" and is full of eerie oddities.

The taxidermy remains of the first mammal ever cloned from an adult cell are on display in Edinburgh.

This futuristically sylvan church is a glass-enclosed marvel of modern architecture.

This giant, 83-year-old ship elevator is an engineering feat to behold.

This long-distance walking route follows the Prime Meridian line as it passes through England.

A mysterious light floating in the trees of Arkansas may be a piezoelectric effect.

The skeletal white beams stand as a monument to religious dissent.

If drivers cross the rumble strip on this stretch of Route 66 at just the right speed it plays "America the Beautiful."