A cave's rare beauty held a cavernous secret hidden underground.

A motel dedicated to Southwestern nostalgia.

This private residence was the template for one of the most beloved television homes of all time.

The marker offers a rare chance to be in four U.S. states at once, though there's some controversy over its geographic accuracy.

This narrow Ghent alleyway is an officially sanctioned street art tunnel.

A public urinal so pretty, it was declared a national monument.

Museum preserving torture methods from the past.

The world's oldest bookshop still in operation.

Legacy of the earthquake that nearly wiped Lisbon off the face of the Earth.

This Industrial Age architectural and engineering gem helps visitors and residents alike traverse Lisbon, “The City of Seven Hills.”

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

In Portugal, a secluded stretch of untouched natural beauty hides at the bottom of a steep hill.

This giant sculpture made of trash is a critique of society's wastefulness.

A hidden three-foot-wide house separates these two regal churches.

This restored Portuguese cafe may well be the most beautiful place in the world to grab a Big Mac.

The arch that celebrated the completion of the Lincoln and Victory highways.

This beloved roadside attraction welcomes visitors with his signature neon smile.

These once-beautiful historic graveyards are set against the barren Virginia City hills.

Beneath a Virginia City bar is the entrance to an abandoned gold mine.

Eastern zen meets Western grit in these four little trees growing out of a rock on Lake Tahoe’s Nevada shore.

An exotic wildlife habitat right off The Strip.

One of the world's tallest Ferris wheels takes visitors high above Las Vegas in a spinning party room.

Las Vegas's very own 40-foot-tall fire-spewing praying mantis.

Standing in a state of "arrested decay," this ghost town allows for a detailed peek into Gold Rush life in an unusually harsh climate.