The enormous 250-room Vanderbilt mansion conceals hidden doors and secret passageways.

This abandoned Brutalist treehouse is a hidden architectural relic.

The largest prehistoric cemetery on the Balearic Islands dates back over 2,500 years.

An ancient Scottish rock formation said to be the gravesite of a giant remains ensconced in legend and intrigue.

A moody and picturesque riverside ruin overgrown with vegetation.

This enormous censer uses a pulley system installed over 400 years ago.

This neon landmark has been posing this deadpan question to follicly-challenged Dubliners for over 50 years.

Twelve hundred stone carvings guard this off-the-beaten-path Buddhist temple.

An unassuming London park is actually a pilgrimage site for modern clowns.

The ruins of an ancient temple to the Aztec wind god discovered in the middle of a metro station.

The Hanshin Expressway goes right through its 5th, 6th, and 7th floors.

Rumored to have tormented a family in the late 1960s, this toy now resides in a quiet little oddities shop.

This macabre monument atop an ancient well gives a nod to a brutal episode in Scottish clan history.

A fantastical 13th-century fortification sandwiched by a modern hotel in central Brussels.

A familiar otherworldly creature guards this 12th-century Scottish abbey.

A network of concealed passageways lies within a busy London Underground station.

The bronzed skull of a beheaded traitor was affixed to the city gate in the 17th century.

Local lore says a serpent-like beast lurks in the deep basin below the falls.

This isolated Japanese mountain village untouched by time showcases unique and stunning traditional architecture.

This tiny movie theater was the last one in the U.S. constructed in the Nuevo Deco architectural style.

A Swiss man built this airstrip for aliens because a UFO captain telepathically told him to.

Hopeless romantics will swoon over the sweet story behind this bright and colorful home.

This modern labyrinth lies in the shadow of a ruined medieval castle.

England's steepest street has such a drastic incline that locals tie their parked cars to lampposts when it gets icy.