A lone cannonball remains lodged in the walls of the Hotel de Sens as a sober reminder of a revolution.

A subterranean shelter remains intact under a busy Paris railway station.

Egyptian Revival movie palace abandoned for decades and restored in 2013.

The Sun King's military models, saved from the Louvre.

The Argonaute submarine was the French navy's pride and joy in the 1950's.

A haunting collection of the vanished and disappearing natural world.

Place with alleged mystical powers in Old Orthodox Church in Sarajevo.

The remains of the last Bosnian fortress to fall to the Ottomans are still standing.

Celebrated example of Ottoman architecture that also served as a site for brutal massacres.

This museum preserves the hand-dug tunnel that kept Sarajevo afloat during the Serbian siege.

These warring psychedelic crags commemorate an unsuccessful military operation.

This cluster of little wooden huts once ground local farmers’ wheat into flour during the days of the Austro-Hungarian Empire.

A charming 17th-century alley is lined with secondhand bookstores and antiquarian shops.

A closed London rail station created to cart away the dead still bears the marks of attempts to make it less morbid.

For this chef, an active volcano is his oven.

A faded reminder of what was once a common sight in London during the Blitz.

This ornate Victorian marketplace was the setting for Diagon Alley and the Leaky Cauldron in the Harry Potter films.

An abandoned tank sits in an empty London lot as a symbolic middle finger to local city planners.

One of London's oldest houses contains a mixture of both old and modern features.

Its collection includes a broad array of social, geographic, graphic design, and political history.

A monument to the thrice mayor of London who according to lore made his fortune by selling his rat-chasing cat.

The 2,000-year-old beam is tucked within the pedestrian entrance to the old London Bridge.

The secret wartime bunker built on the platforms of an abandoned Tube station.

Dictionary Johnson’s favorite feline.