Seven mini rowhouses fill the gap between 54 and 70 Westerstraat.

This 22-floor tower's Skydeck offers panoramic views of Amsterdam.

This hydrochronometer was invented by a Dominican monk and is a prime feature in this garden.

This subterranean shrine beneath a bike rental store celebrates the iconic Italian scooter.

A forgotten "city of water" underneath the famous Trevi district.

A magnificent waterfall is also home to the remains of a Roman hydraulic engineering system.

This large, circular tomb is the final resting place of the first emperor of Rome.

Inside this McDonald's you can dine on your Big Mac and fries next to a 2,500-year-old Roman wall.

The spot where the fascist dictator made some of his most famous speeches including declaring war on Britain and France.

One of several skulls claiming to belong to the beheaded St. John the Baptist is on display at this Roman church.

This beautiful park on the outskirts of Rome protects the ruins of two colossal ancient aqueducts.

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

This demon atop the Notre-Dame de Paris looks utterly bored.

Inside a former cabaret, seven floors of erotic art.

The celebrated eyesore created by starry-eyed sweethearts.

One of the last umbrella repair shops in Paris upholds the nostalgic art of umbrella making.

A glamorous hotel that once accommodated French resistance fighters and concentration camp survivors.

This lesser-known Frank Gehry building houses a treasure trove of cinema history.

Claude Monet was baptized in this lavishly ornate Paris church.

A mud statue stands in the dark tunnels, seeming to hold up the weight of the city above.

Collection of antique taxidermy and natural specimens, near one of Paris's oldest flea markets.

This recessed garden protects thousands of mountain plants by creating its own microclimates.

What looks like a normal building is really a hollow facade hiding a subway vent.

Ordinary art transforms to extraordinary thanks to locals' quirky sense of humor.