Deep scars on the earth left by the Ice Age.

Big gun installations, built over a massive cemetery, now abandoned & hidden in trees.

The one-time watch house for incoming ships at the Golden Gate now stands abandoned and hidden in trees.

A winding path built in secret on the edge of the continent.

The oldest surviving bridge in New York City, which reopened to pedestrians in 2015.

Huge concrete structures designed as an early warning system for Britain to detect enemy aircraft.

Lovers proclaim their unbreakable bond by leaving their names on locks fastened onto the Shoreditch fence in East London.

Once the fastest ship from San Francisco to Tahiti, the Galilee now lays in pieces in three different cities.

Architect Le Corbusier built his friend a cubist house to match his impressive collection of cubist art.

Created by one of England's most prolific labyrinth designers, inspired by Bath city history.

An Escher-inspired library dedicated to the wonders of the human mind, yet closed to the public.

A vast collection of rare books, manuscripts & extraordinary objects illustrating the history of medicine.

The memorial to the victims of the Jonestown Massacre carries the names of 918 lost, including one name people wish wasn't there.

A writer's tiny retreat built from salvaged shipwreck timbers.

A picture-perfect town, perfect for blowing up.

This small collection of rare books was uniquely locked up for safe keeping.

A petite castle folly in the English countryside.

The largest whiskey stash on the West Coast survived the 1906 fires--but not without heroic effort.

The longest living non-clonal organisms on Earth.

16,500-acre ranch filled with American heritage, geological wonders, and a giant pile of tires is the crown jewel of an intriguing tug-of-war.

One of the oldest libraries in England, and one of the last of the great medieval chained collections.

On October 17, 1814, a 15-ft. wave of beer ran rampant through the streets of London.

The site of one of the strangest disasters in history—a wave of deadly molasses traveling at 35 mph.

This impressive tunnel was dug entirely by hand over the course of 36 years.