The underground sanctuary of a mysterious ancient cult.

The only "Egyptian" pyramid in Europe and the legendary tomb of Remus.

A master of trompe-l'oeil creates a stunning, tourist-fooling dome out of a flat ceiling.

Hundreds of lucky felines haunt the ruins where Caesar was murdered.

Remnants of cone-shaped fascist bomb shelters in Milan.

The mark of the Devil's horns on a marble column in Milan.

The secret medieval communication system will whisk your words above the noise of the crowd.

Small on the outside, big on the inside, this church is an astonishing act of visual deception.

This giant middle finger statue sends an unambiguous message to Italy's bankers.

An ossuary built in 1210 to collect bones from the Ospedale Maggiore of Milan.

When you're a great Russian Tsar, even your vomit gets a statue.

A fantastical 13th-century fortification sandwiched by a modern hotel in central Brussels.

This modern arts center is built around a gem of late-Baroque architecture.

Lavish royal estate punctuated with heated greenhouses.

This collection of over 50 murals celebrates Brussels' rich history as the self-proclaimed home of the "comic strip."

This one has sailed five times as far as Sir Francis Drake's famous ship.

The watery entrance for condemned prisoners heading to the Tower of London is still visible along the Thames.

Mary Kelly was last seen here before she was murdered by Jack the Ripper.

This massive collection of British military artifacts includes the heartbreaking personal letters of the men in the trenches of WWI.

An incarceration museum on the spot of possibly the oldest prison in England.

Hear the quietest sound from across the dome.

An unusual round church in London with a Templar past.

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

This winding road of 318 curves is a must-visit for (careful) motorcycle and sports car enthusiasts.