In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

Perhaps the most spectacular grotto along the Algarve coastline.

This unassuming chapel in Portugal plays host to a ghoulish collection of bones.

The western face was supposedly left clock-less to snub the Welsh.

The quiet field that inspired one of the most famous songs of all time.

This abandoned lock-up was saved because of its connection to a local football team.

The red letters in the literary pavement leading to the library form a mysterious code.

Charles Dickens described the concert room in this amazing Victorian hall as "the most perfect room in the world."

This whimsical public art installation is a unique homage to Liverpool's industrial heritage.

Abandoned ship reimagined as a street art canvas.

Most of Britain's gold reserve was secretly stashed here after the start of World War II.

The tower was originally used as a chimney for the waste incinerator of St. John's Precinct and Market.

Created as a punny statement about genetic engineering this monstrous hybrid statue has become a beloved icon.

The grand complex of buildings that comprise Liverpool's Exchange Flags includes a vast World War II bunker that has been frozen in time.

This aging storage facility is the world's largest brick warehouse.

A little sculpture with a large wardrobe.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

A contemporary art installation housed within a Gothic cathedral.

A magnificent, glittering building tucked into a tiny Bulgarian mountain town.

A mountain pass in Bulgaria's Balkan Mountains was the site of four historic battles.

An abandoned saucer-shaped monument in the Bulgarian mountains.

This derelict superstructure was a very important warning system for the Soviet military.

This attraction was abandoned after the Chernobyl disaster.

One of the most poignant ruins of the Chernobyl nuclear disaster, the local football team's stadium has been quickly reclaimed by nature.