At the largest railway museum in the United States, you can see everything from an early steam engine to a functioning Thomas the Tank Engine.

A tribute to one granddaughter's old apartment which now represents the whims of each visitor.

This $3 million model train takes you through Chicago, Seattle, and the thousands of miles in between.

This surprising gem is a world-class archeological museum hidden at the University of Chicago.

This bronze sculpture on a former squash court marks the secret origins of the Atomic Age.

A lush green oasis in the middle of Chicago.

Fragments of architectural wonders from around the globe are embedded in the newspaper building's walls.

The twin towers in this Chicago fountain use 50 foot tall video screens to spit on people.

Each of these gorgeous, intricately decorated rooms is painstakingly crafted to the scale of 1 inch: 1 foot.

This historic hotel invented the chocolate brownie.

It holds a fabulously designed tribute to astronomer Edmond Halley.

The perfectly preserved underground rooms where Churchill plotted the war against Germany.

The sumptuous ceiling was one of the last things Charles I saw before his execution.

This coffee shop lies hidden beneath a historic church.

The curious underground history of keeping Paris clean.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

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

A magical, macabre wax museum, beloved by locals, uses real artifacts to depict an assassination from the French Revolution.

This 18th-century sundial was designed to calculate the date of Easter each year.

A 400-year-old church covered floor to ceiling in ex-voto offerings from the faithful.

Remains of Roman amphitheater hidden in a sleepy quarter of Paris.

Medieval museum built over Roman baths that features famous tapestries of a lady and a unicorn.

19th century pendulum and a clock restored by a rogue group of guerilla artists.

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