A hidden art gallery in an abandoned Warsaw fort.

A huge wooden clock that is so beautiful its creator was forcibly blinded.

After the famous composer died in Paris, his sister snuck his heart out of the country to honor his wish that it be buried in their native country.

Warsaw's fantastically preserved gasworks...almost.

A program of Communist glamour in post-Stalin Poland is preserved in this colorful museum.

The site of the first battle of World War II.

The walls and ceiling of this Polish church are decorated with thousands of skulls, with another 21,000 skeletons just below.

Beneath Kraków Old Town's main square lies a hologram-filled medieval market vampire graveyard wonderland.

The Metropolitan Police refurbished the blue box (perhaps not coincidentally) the same year "Doctor Who" returned to TV screens.

A student driver's nightmare.

Hidden beneath the streets of London is a secret subway that only carried mail.

When the river dries up, these stones start talking.

Before serving as James Bond's Casino Royale, this Victorian-era spa catered to the world's elite.

An unusual bronze bus shelter is actually an art installation commenting on the city's history with the Nazi party.

A mesmerizing landscape of 18th-century cellars carved out of the land.

A larger-than-life statue of the German revolutionist stands proud in a small town where he never lived.

A Cold War secret surveillance tower used to spy on radio communications.

This Czech military museum is home to pink tank that was once a symbol of art and political rebellion.

The sanctuary holds what was once believed to be the saint's incorruptible tongue.

This renaissance château was home to an infamous witch hunter who sent a hundred suspected witches to their deaths.

An army of sleeping knights sculpted by a self-taught local artist beautifully depict an old Czech legend.

The largest manmade caves in Europe now function as a motorbike club's headquarters.

Every part of this unusual home is built into the sandstone rock.

A cheeky architectural easter egg.