A Portuguese Jewish cemetery filled with stunning grave monuments that date back to 1614.

It appears as if a man is standing behind this giant airport clock, painting the hands in real time.

This mosaic dedicated to John Lennon was tended for years by a Beatles super-fan.

Follow the original medieval paths that wind through this intriguing section of the city.

The largest greenhouse in the world is home to over one million types of plants.

Eighty million natural history specimens call this gargantuan museum home.

An intriguing three-sided folly is a testament to one man's devotion to Catholicism and the number three.

You'd never know the houses at 23-24 Leinster Gardens were fakes—until you see the train tracks on the other side.

The only university zoological museum in London houses extinct animals, bizarre natural history specimens, and a Micrarium of microscopic creatures.

A student driver's nightmare.

The narrowest street in Paris.

The water-powered carriages are long gone, but for over a century this funicular railway has been the fastest route to the highest point in Paris.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

High atop the Eiffel Tower is a small apartment built exclusively to entertain the science elite and make the rest of Paris jealous.

The very center of Paris is surrounded by a bevy of strange good luck rituals.

Paris' linguistic guide to the international language of, yes, love.

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

France's most famous cemetery, with some of its most curious tombs.

For decades, Puerta del Sol has been illuminated by a giant, guitar-wielding bottle of sherry.

This sweet-toothed bear searching for snacks has been a symbol of Madrid for decades.

A lush indoor jungle fills this bustling Madrid transportation hub.

A vista of the city and sea from atop the little-known viewing deck on an unassuming Columbus statue.

These secluded and abandoned anti-aircraft defenses have become one the most scenic viewpoints in Barcelona.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.