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

An intricately designed junk art house with four extravagant junk art cars hidden in the suburbs.

The world's oldest continuously operating airport was founded by the Wright Brothers.

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

Every drop of D.C. tap water flows through this old waterworks.

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

Members of Congress have traveled between the buildings on Capitol Hill for a century hidden from tourists, press, and storm clouds.

Decades before the scandal, this staircase on the river was a literal "water gate."

A historic ruin just 20 feet away from a busy highway onramp.

The site of the climactic scene from the classic horror film is now a historic landmark.

This English-inspired Maryland garden is home to acres of opulent plant life including bushes shaped into an entire fox hunt.

Nightmarish example of the unintended consequences of weapons testing.

Despite violent work crews and massive delays this abandoned canal tunnel was built to last into the modern day.

This abandoned asylum was once a state of the art facility before devolving into one of the most deadly mental institutions in American history.

Carved fountains poignantly placed in parks and in front of special monuments.

The oldest museum in Russia is home to a fascinating collection of nearly two million anthropological artifacts and anatomical curiosities.

A 250-year-old timepiece-automaton adorned with golden mechanical birds, which still sing to this day.

The oldest church in the Estonian capital is home to over 100 fantastical cemetery coats-of-arms.

The Guardian of Tallinn.

"There's nothing there," and other lies the KGB told us.

A monument marks the location of the first successful steamboat demonstration.

The last holdout of a pre-Civil War rebel who took the matter of slavery into his own hands.

A star fort along the C&O Canal in western Maryland that protected America in three wars.

A cave on the Maryland border where civilians took refuge during the bloodiest battle of the Civil War.