One of the largest underground systems runs under Canada's largest urban center.

The Incredible Hulk, Yoda, Mulder and Scully, and many many others watch over the mean streets of Toronto.

This inexpensive lodging house was once a prison notorious for its inhumane practices.

The mastermind behind this palatial hotel perished on the Titanic weeks before its grand opening.

Louise Bourgeois' 30-foot-tall steel spider sculpture.

Every year, the colorful murals of Montreal get a complete makeover.

This steep cable railway has been hoisting passengers in the heart of Québec City for over a century.

This lovely, if imposing, piece of Canadian gothic is possibly the most photographed hotel in the world.

The beloved statue at the National Academy of Sciences is oh so inviting to sit on.

This triumphal arch celebrating the Sun King's conquest of Lille is a masterpiece of military architecture.

This statue honors the thousands of Allied avians that served and died for France during World War I.

The popularity of Sherlock Holmes led to the creation of his fictional address, turning the orderly London street numbers askew.

Eighty million natural history specimens call this gargantuan museum home.

Hundreds of hidden passageways weave through the old quarters of Lyon.

For hundreds of years, automatons moving to metallic music have been marking the passage of time.

Lyon, France is home to two remarkably preserved Roman theaters, one dating back to 15 BCE.

There has been an astronomical clock on this spot since the 14th century.

First point in the Struve Geodetic Arc, a 19th century undertaking to measure the Earth's size and shape.

A subterranean house of worship carved right out of the bedrock.

From Austrians to Nazis to Soviets, this historic Budapest fortress has a history as complex as the city itself.

A trail of iron footwear stands as a monument to the thousands executed along this riverbank during WWII.

Museum dedicated to the terror regimes of Hungary.

This series of Baroque passageways in Vienna's cultural center mix old architecture with modern art.

The beautiful, ornate weather station is the most popular geocache in Salzburg.