This ruined fortress was the stronghold for a persecuted medieval leader and his infamous Assassins.

A creepy sculpture of a decapitated head invites viewers to see St. Louis through its empty eyes.

With nearly double the depth of the Grand Canyon, this Peruvian canyon is one of the deepest in the world.

The 16th-century church was kept in its ruined state as a reminder of the casualties of World War I.

A Gothic-style abode built to accommodate the church's three resident peacocks.

Things aren't quite what they seem at this mind-bending museum.

This Seattle joint serves food inside an old train car once used by FDR.

The complex has been abandoned since the Croatian War of Independence, barring a stint as a set for 'Game of Thrones.'

Dozens of lights dangle from the branches of what may be the brightest tree in Los Angeles.

Science meets wall art to highlight the beauty of famous mathematical equations.

Once in disrepair, this popular Texas stop along iconic Route 66 has been restored to its past glory.

A serpentine highway twists and turns over the treacherous Norwegian Sea.

A raised boardwalk winds through a thicket of stunted, century-old trees no more than nine feet tall.

Every summer local children form "pysja patrols" to save young birds that have wandered from their nests.

A visionary Italian architect created an impressive cluster of concrete structures for a family's private tomb.

A cave 150 feet beneath Kansas City is the perfect climate for growing 10,000 delicate orchids.

At the United Kingdom's only residential library you can sleep among the books.

The unedited photograph called "Bliss" has graced the screens of over a billion computers.

A thick blanket of beautiful pampas grass cloaks this unique Japanese landscape.

These ancient sunken lanes were naturally tunneled into the soft ground by countless footsteps.

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

The vertical-axis windmills of ancient Persia have been grinding flour for 1,000 years and counting.

A Frankenstein blend of science and art allows one tree to produce 40 different types of stone fruit.

A perfect circle of 24 mysterious holes dates back to prehistoric times.