An architect's childhood fantasy treehouse made real.

This geometric feat is a testament to the Incas' mesmerizing architectural abilities.

The blinking light atop the iconic landmark has been sending secret messages for decades.

The second oldest continuously operating bar in Louisiana.

Hear the quietest sound from across the dome.

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

What appears to be an ancient Roman temple is actually a Catholic church.

An ancient Roman temple first dedicated to an emperor's wife is now a church.

This curious, round temple is the oldest still-standing marble building in Rome.

Historic funicular railway, believed to be the shortest railroad in the world.

Although he donated over 3,000 acres to Los Angles, Griffith's life was marred by controversy.

Pilgrimage site for star-crossed lovers.

This Estonian watchtower looks like a big tree with two giant bird nests on it, complete with a "golden egg."

This old and disused water tower has received a new life as an art gallery with a piano staircase.

For the last century, this international border within a small town has appeared and disappeared various times.

A snapshot of the city's fascinating voodoo culture.

Flashy signs from Las Vegas’s past find their final resting place at this unusual graveyard.

A kaleidoscopic warehouse-maze of handmade neon signs.

The unique waterfall in Iceland's south features a backdrop of geometric black lava columns.

Medicinal spa created from the mineral-rich runoff of a geothermal power plant

A sharp bend in a dramatic river canyon cut through red rocks.

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

Disney's abandoned animal island is now an overgrown ruin that was almost the coolest attraction ever.

The reconstruction of this prominent building fulfilled a long-written command.