This abandoned gun tower was built to defend the River Thames from a French naval attack.

The abandoned fishing village was swept right into the sea.

The abandoned funicular tunnel was a secret base for the BBC during World War II.

The dramatic remains of an abandoned farmhouse sit high on the edge of a remote hillside.

An abandoned World War II tank left to rust in the downland.

Britain’s highest medieval monastery is a remote ruin nestled at the head of a valley 1,240 feet above the sea.

A relic of Victorian grandeur hides beneath a busy South London road.

The abandoned railway bridge stands hidden in the farmland of rural Cumbria.

The remains of a remote village that once housed over 1,200 dam workers and their families.

Now a memorial to merchant sailors and Titanic victims, this medieval church was destroyed by bombing raids in 1940.

This medieval manor house was hastily fortified when it found itself in the middle of the Scottish fight for independence.

A labyrinthine underworld of tunnels and caverns hides beneath the city.

This historic building displays the remains of a victim of the devastating 14th-century plague.

A little-known ruin with a convoluted history and a fascinating latrine drainage system.

The bizarre visions of H.R. Giger, tucked away in a Swiss medieval city.

This medieval sanctuary's tree-framed door looks like a portal to a mythical realm.

The longest continuous lava tube in the continental U.S. offers 2.5 miles of dark explorations for the adventurous.

This iconic L.A. bookshop is housed in an abandoned bank—both symbolic and chic.

Non-profit time travel mart sells goods you would need for a trip through the fourth dimension.

During prohibition, corrupt city officials ran drinking dens under the streets of Downtown Los Angeles.

The lighthouse central to the 1980s horror classic "The Fog" is, in fact, located in one of the foggiest areas of the Pacific Coast.

A collision of human error and natural geothermal pressure created this rainbow-colored geologic wonder.

A subterranean world of tunnels links several buildings of this rare 19th-century asylum.

Street artists transformed this abandoned industrial neighborhood into one of Europe's largest graffiti exhibitions.