A horde of stray cats rule in this secluded Parisian cemetery under a bridge.

The narrowest street in Paris.

These steps offer a breathtaking view of one of Europe's most besieged fortresses.

A unique seaside cave where Aleister Crowley faked his own death.

An ancient and majestic fortress that played an integral role in Portugal's road to independence.

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

Sip cherry liqueur at a bar dating back to 1840.

Portugal's National Pantheon has a history of curses, collapses and financial problems.

This Industrial Age architectural and engineering gem helps visitors and residents alike traverse Lisbon, “The City of Seven Hills.”

A king's pet, a pope's gift, an artist's inspiration, and a tragic shipwreck.

This charming candle shop has been in business since 1789.

Legacy of the earthquake that nearly wiped Lisbon off the face of the Earth.

This magenta statue commemorates the legendary marriage between a mermaid and the city's founder.

An expansive complex of subterranean tunnels is all that remains of one of Europe's most formidable medieval fortresses.

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

The curious underground history of keeping Paris clean.

Noirish green neon marks the location of one of the oldest private detective agencies in France.

This ornate Victorian marketplace was the setting for Diagon Alley and the Leaky Cauldron in the first ‘Harry Potter’ film.

One of the few remaining casualties of the London Blitz, this destroyed church has become an enchanting public garden.

A memorial in the Tiergarten is a reminder of the suffering inflicted on homosexuals by the Nazi regime.

A tribute shrine where the Space Invasion street art movement started.

This narrow Ghent alleyway is an officially sanctioned street art tunnel.

This fairytale castle was built as a show of power but was nearly torn down thanks to its history of torture.

Monument to a brutal, ineffectual US bombing campaign and a sobering reminder of the human cost of the Vietnam War.