This Hungarian castle was built out of cardboard and wood until it proved so popular that it got upgraded to stone.

A whimsical village of unique treehouses resides in a Washington forest.

The final resting place of the poets Shelley and Keats.

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

Though its celestial ceiling is impressive, the true star is the vast collection of French books.

One of the oldest used bookstores in the U.S. has been selling antiquarian treasures since 1825.

This 1967 experiment in modular architecture was designed to be a new model for urban living.

An abandoned saucer-shaped monument in the Bulgarian mountains.

This ancient village and its adjoining cemetery have a beautiful history of death and remembrance.

The ruins of this antebellum sugar plantation are the end result of a Seminole attack during the Florida Wars of 1836.

A former utopian healing center created by a huckster and built by derelicts.

An ultra-modern diversity park in Denmark has turned an entire city block electric pink.

One of Ireland's most infamous prisons for rebels including men, women and children.

Hidden in plain sight on the Hudson River is an abandoned train station where nature has taken over.

The remains of diamond fever taken over by the desert.

An overlooked marble is the only surviving in-place 18th century example of the measurement that changed how we define distance.

Intensely colorful calcite pools in Southern China.

A beautiful oddities shop crammed with strange and morbid curiosities.

An abandoned quicksilver mining town surrounded by the Big Bend parks.

A grand Gothic Revival basilica with stained glass depictions of Montreal's religious history has only one soul resting in its crypt.

Terrifying derelict military hospital once housed a recuperating Hitler.

This Philly cemetery is the eternal home of many famous area residents, including Rocky Balboa's wife.

An experimental, automotive replica of Stonehenge.

Once the "Eighth Wonder of the World," this iron railroad bridge was decimated by a tornado.