Constructed by forced laborers, this submarine pen is now a museum and war memorial.

This disused Cold War bunker has been restored to all of its early 60s glory.

This top secret Chinese military megaproject is the world’s largest human-made tunnel structure.

Part of a secret 1970s nuclear defense program is now open to the public.

The remnants of an early American attempt at missile defense.

A former top secret nuclear fallout shelter now operates like a hotel stuck in the Cold War.

A nuclear bunker built to shelter the politicians and important people of Scotland in case of nuclear attack.

On a site with a long military history, a 1980s shelter.

Below a historic English market town lies a secret underground city complete with kitchens, laundries, storerooms, and an underground lake.

This Cold War–era underground city includes offices for Mao Zedong and Lin Biao.

The biggest and deepest Cold War bunker open to the public can be found in southeast England.

Tibetan-influenced mountain fortress in Northern Pakistan.

The Great Wall of Sindh, Pakistan's mighty fort.

The third largest ship breaking yard in the world has created an eerie shipping graveyard in southern Pakistan.

A tower built by an emperor for an antelope.

A 17th-century mosque that was used for war more than worship.

A place as enchanting as the journey to reach it is harrowing.

This grand Pakistani mausoleum can only be accessed via an almost 1,000 foot long alleyway.

These stairs were built to accommodate royals mounted on elephants.

One of the largest necropolises in the world is home to a stunning array of historic Middle Eastern tombs.

Massive fortress bastions in the desert of Cholistan.

The world's second largest salt mine, said to have been discovered by Alexander the Great's horse.

A Moroccan getaway in the mountain range that plays the Himalayas' stunt double.

This abandoned nitrate town was repurposed as a dictator's prison.