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

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

A king's pet, a pope's gift, an artist's inspiration, and a tragic shipwreck.

This scented city oasis was a labor of love.

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

Single runway interrupted by a busy road that cuts across its middle.

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

The first bell ever cast in Boston was cast by Paul Revere...and sounded terrible.

The site of Paul Revere's historic two lantern warning.

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

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

This innocuous New Mexico storefront was once the secret jump-off spot for Manhattan Project scientists.

Wedding chapel's mysterious spiral staircase said to be miraculously constructed.

An immersive environment that is part haunted house, part choose-your-own-adventure, and part jungle gym.

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

This nine-story building can be played like an instrument.

There is no trying to fall in love with this Star Wars fountain, you just do or do not.

The future of roadside attractions is this sci-fi soda mecca that is home to a 66-foot tall neon pop bottle.

On any given day this sprawling market houses literally tons of government-regulated gold, gems, and precious metals.

A series of caves under Castle Hill that once held the prisoner Vlad Tepes, better known as Count Dracula.

This replica Viking village was created for a film that was never shot and is now open to visitors.

This valley of hot springs and boiling mud pots is home to the record-holding "Geysir," which originated the English word.

This elegant arc of a waterfall marks a religious turning point.