A centuries-old complex of hand-dug stone chambers has sheltered locals in times of trouble.

An underground city of ancient quarry tunnels hid thousands of Allied soldiers in WWI.

A monument to the thousands of Canadian soldiers who died capturing the French ridge during World War I.

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

Twelve grave-faced marble angels guard the emperor's tomb at Les Invalides.

This old, abandoned hotel offers magnificent views.

The dining hall that nourishes workers in Chernobyl's Exclusion Zone is also open to visitors.

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

This attraction was abandoned after the Chernobyl disaster.

The biblical sculpture honors those who lost their lives, homes and communities to 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.

This small red school was where Germany signed their surrender during WWII.

The building is a gigantic piece of art inspired by the shape of a desert rose.

Qatar's oldest market can trace its origins back more than a century.

This unique museum doesn't shy away from highlighting Qatar's role in the history of slavery.

This 23-foot-tall bear stands amid the hustle and bustle of Hamad International Airport.

A superb spot to appreciate the traditional boats of the Indian Ocean.

This fountain pays homage to Qatar's history of pearling, the primary industry before oil.

The water-powered carriages are long gone, but for over a century this funicular railway has been the fastest route to the highest point in Paris.

A reconstructed medieval gateway that was the magnificent entrance to the capital city dating back to 1037.

340-foot statue built to honour the Heroes of the Soviet Union.

The deepest metro station in the world.

One of the largest museums in Ukraine remembers the story of the German-Soviet War in iconic, brutalist style.

Five million people are laid to rest here, more than the population of Madrid itself.