A monument in Washington D.C. marks the spot from which all other roads were supposed to stem.

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

A 1,100-ton train fell through the floor in 1953. Workers got it patched up in just 72 hours.

This mysterious structure by the Washington Monument is a flood barrier designed to protect the White House against rising waters.

A derelict bit of infrastructure from the canal that once ran through D.C. is landlocked in the heart of the city.

One critic described it as "middle Mussolini, early Ramses, and late Neiman-Marcus." Another called it an architectural "natural disaster."

A promising candidate for the lost rock laid by George Washington was unearthed, but the hunt is still on.

There’s a special club house at the top for the bell ringers.

The elevator that makes it possible to fly American flags in bulk over the U.S. Capitol

An easily overlooked memorial to a Ukrainian famine-genocide that killed over 4 million people.

A clone of a cloned tree that was so important it allegedly had its own guards.

The most accurate timepiece in the world.

Cold War intelligence agents monitored communist embassies from an attic in a former pigeon coop.

A celebrity from the late Cretaceous period.

More sculpture than building, this architecturally significant temple was built on the spot of Saint Peter's crucifixion.

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

Rome's semi-secret peephole vista is also a former Crusader stronghold.

The oldest (maybe) swimming pool in Iceland is a stunning oasis built into the side of a lush hill.

At 207 feet, one of the world's longest continuous escalators.

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

These locks on North America’s oldest canal are named after a porcine rock formation.

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

Unable to build support structures on glaciers, the engineers for this tramway were forced to design a unique system.

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