Once home to seven different roller coasters, Glen Echo has undergone many transformations since its founding in 1891.

One artist's love letter to his city and its citizens plays out across dozens of bright murals painted on the sides of decrepit buildings.

One day a year it is legal to jump off of this astoundingly tall bridge that spans an Appalachian gorge.

The "mysteries" of this quintessential roadside oddity were almost destroyed by neglect but were saved by fans of kitschy wonder.

The oldest continuously operating fish market in the United States.

The land is home to swimming ponies and a legendary 18th-century treasure.

An organ located deep within a cave, whose "pipes" are the geological features of the cave itself.

An enormous warehouse filled with parade floats collected from over 50 years of patriotic celebrations.

Crammed into a Baltimore row house is an oddities shop that sells everything from skulls to dead insects.

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

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

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

The little-known, 300-year history of the area includes former lives as a bustling tobacco port, parking lot, and industrial dump.

This seemingly out-of-place gas station by the Watergate hotel was once described as the most expensive gas station in the world.

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

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

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

Architecture lovers won’t stop touching the National Gallery's 19.5 degree marble prow.

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

The national park was once a plantation estate.

The most accurate timepiece in the world.

A nostalgic bibliographic gem.

A lovely aquatic park built by a one-armed Civil War veteran who made a fortune from lotuses.

During the Industrial Revolution this “Temple of Invention” was full of intricate miniature machines and gadgets.