While most wind tunnels test scale models, the "Cave of Winds" was large enough for actual airplanes.

This stunning blue and gold room changed cities twice before becoming part of the Smithsonian.

Perhaps the most scandalous statue of America's first president.

Legend has it that President Grant’s frequent drinking in the lobby gave rise to the term “lobbyist.”

A line of blue paint marks the route of the inaugural parade.

A bas relief commemorates the "Nuns of the Battlefield" who cared for soldiers on both sides of the conflict.

The sculptor was instructed to add “stallion attributes” to the general's bronze mare.

Giant acorn-shaped 19th century gazebo from which suburban Washingtonians gazed upon the original "silver" spring.

The country's oldest continually-operated mini golf course lies hidden in plain sight, eclipsed by one of D.C.'s most popular tourist attractions.

Richard III supposedly disposed of his nephews' bodies here in an effort to seal his claim to the throne.

This unique historical monument features large concrete spheres designed to resemble fallen stars.

Twelve grave-faced marble angels guard the emperor's tomb at Les Invalides.

High atop the Eiffel Tower is a small apartment built exclusively to entertain the science elite and make the rest of Paris jealous.

An unsanctioned shrine that sprung up outside the late singer's home is causing a stir in London's Highgate neighborhood.

Six ravens are kept captive (but well-fed) at the Tower of London to prevent the fall of the Crown.

Rebuilt remains of a temple to Roman god Mithras.

This gorgeous reading room houses the oldest and largest art history library in the Netherlands.

The system of air guns are fired off remotely to scare any trespassing avians.

This rare triple-jurisdiction drawbridge passes through Virginia, Maryland, and Washington, D.C.

Right next to departures—how convenient!

The Pentagon sits on a former island that was in Virginia at low tide and D.C. at high tide.

This church built atop a gas station promises to "equip you for the next stage in your life’s journey."

The oldest building in the District of Columbia was preserved because of a mistaken connection to George Washington.

‘Bush the old fire dog died of poison July 5th, 1869. RIP.’