Museum celebrating the achievements of the Soviet space program.

A kaleidoscopic warehouse-maze of handmade neon signs.

An abandoned swimming pool decays on the outskirts of Berlin.

An abandoned NSA listening post on Berlin's "Devil's Mountain."

A licentious look into Singapore's past, full of disorderly bric-a-brac and disreputable characters.

The largest pool at its elevation sits on top of one of the most expensive resorts in the world.

Hidden beneath a restaurant, underground tunnels tell the story of Malta’s tragic role in World War II.

This almost-forgotten underground dungeon housed several convicts over the years, including Caravaggio.

The medieval home is still engraved with the symbol of the profession, an eye flanked by two axes.

A centuries-old forgotten underworld lies beneath Malta.

The Jesus tree of Malta bears a striking resemblance to Christ on the cross.

A hidden tunnel of bones in one of Malta's oldest churches.

This prison on the Maltese island of Gozo is almost 500 years old, and they have the graffiti to prove it.

Stone Age solar temple is aligned with the sun on each equinox and solstice.

An abandoned set from the 1980 film "Popeye," claimed and repurposed as a theme park by creative locals.

The curious underground history of keeping Paris clean.

A museum on the history of Paris, including a set of Napoleon's toiletries, Proust's room, and relics of the Revolution.

An off-the-beaten-path boutique stuffed with an eclectic collection of upcycled goods.

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

A favorite Paris bar for U.S. expats, including Gershwin, Hemingway, and James Bond.

A museum of magic with a Sadist past.

A museum of carnival attractions where you are invited to ride the rides.

Abandoned railway line circling the city of Paris.

The macabre collection of Jacques Sirgent, an expert scholar on the undead and all of their trappings.