Site of a classic 19th-century physics experiment to prove the earth is rotating.

The tradition of open-air secondhand and antiquarian bookselling in Paris dates back to the Renaissance.

This modest marker near Notre Dame identifies the very center of Paris.

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

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

One of Catholicism's four major basilicas has a series of papal portraits that are said to predict the end of the world.

2300-year-old Roman road connecting the empire.

Breathtaking and huge 430 year old maps of Italy.

This equestrian statue of Constantine the Great has been the subject of criticism for centuries.

Hidden beneath the famous St. Peter's Basilica is a veritable city of the dead that may hold the remains of St. Peter himself.

The first statue to be added to Saint Peter's Square in over 350 years is an ode to migrants and refugees around the world.

The remains of this 2nd-century Roman temple are incorporated into a modern building.

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

A detailed pachyderm supports Rome's smallest Egyptian obelisk.

A small but very fascinating fountain in the center of Rome with four books and a deer carved.

Stone memorial that's said to predict the death of the pope and the site of the Cadaver Synod.

An ancient Roman temple first dedicated to an emperor's wife is now a church.

A UFO-shaped event building originally intended to be a science museum showcasing the future.

This strange building looks like a medieval fortress crashed into a 1960s Brutalist office block.

Oldest World War 2-themed museum in Western Europe.

A floating cat sanctuary on an Amsterdam canal.

A miniature city, once ruled by the Queen of the Netherlands.

The birthplace of most all of Europe's space missions is here on the Dutch coast.

Rich with fauna and flora, nature-lovers can walk across the sea at this UNESCO World Heritage spot.