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

This attraction was abandoned after the Chernobyl disaster.

The ghost town left by the worst nuclear disaster of all time is being taken over by nature and urban explorers.

The now-quiet remains of coastal artillery defenses that were used in both World Wars.

The bears of Bern have been a city highlight for over 500 years.

The second-highest train station in Europe.

Caves famous for the dragon-slaying saint who lived there.

Ring the bell to enter a bar that looks equal parts museum and old curiosity shop.

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

This unreal Portuguese palace looks as though it's made from a pile of different castles.

An ancient and majestic fortress that played an integral role in Portugal's road to independence.

An ancient necropolis of magnificent tombs.

The ancient mosaics here are considered among the finest in the world, and serve as a stunning record of Greco-Roman daily life.

This ominous Albanian fortress houses tanks and downed planes as a reminder of their victories over Western imperialism.

Take respite inside this jaw-dropping church while climbing the volcano where Georgia's Prometheus was once chained.

A cylinder monument with a spectacular vista commemorates a friendship that some say never existed.

An ancient church on a tiny island covered in stone bible stories has controversially been turned into a museum.

The highest peak in all of England is plagued by dangerously fickle climate shifts.

This historic square in Nepal is home to temples dating back to the third century.

The fishing boats that moor in this small lagoon enter and leave through a tunnel to the sea.

Two geological phenomena in one precarious locale: a towering stone window, and a deep blue void.

An ancient sanctuary that has long been a holy site for the Chaldean Christian Church.

The sacred shrine of the Yazidis.

A bloody history is captured in this former prison turned museum.