A muscular Art Deco monument represents the struggle between regulators and unbridled markets.

Look closely and you’ll notice that the color changes a third of the way up the tower.

Those with a sharp eye can find the hidden image of a German Shepherd on the memorial's Mural Wall.

An overlooked oasis of quiet on the grounds of Washington's monumental basilica.

Home to a vast and influential collection of Shakespeareana.

Largest Roman Catholic church in North America.

The Byzantine, pre-Columbian, and medieval art at this stately mansion are some of the most under-appreciated collections in D.C.

A tiny piece of the Moon is embedded in this stained glass masterpiece.

Home to items never before seen by the public.

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

The celebrated eyesore created by starry-eyed sweethearts.

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

The video game-themed street art first popped up in the French city.

Saintly bones pressed into a wax effigy of a Catholic superstar.

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.

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

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

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

This massive library holds what was once the largest book collection in the world.

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

A hidden treasure in London with a rich medieval history, and the resting place of many luminaries.

A labyrinth hides in plain sight at each of the city's 270 Tube stations.

Never actually a tree at all, this spot was the site of London's public hangings for nearly 600 years.

The library houses an incredible collection of some of the world's most impressive books and manuscripts.