This sculpture by artist Fritz Keonig survived the 9/11 attacks and now stands as a monument to the victims.

A beautiful and abandoned New York subway station from 1904, complete with chandelier.

An uber-secure, windowless tower of doom in the center of Manhattan is an NSA spyscraper.

Historical figures from New York City's Catholic community reside in Midtown.

A dilapidated dock tells the story of Titanic's missed arrival.

Elevated freight railway turned wildly successful urban park.

This elaborate towering structure was once famed for its revolutionary height.

America's most famous museum of medical oddities is home to the remains of Albert Einstein's brain.

A tour de force of a fountain, memorializing a man who loved fountains more than anything else.

World's first "penitentiary," meant to be humane, drove men insane.

Yo, Adrian!

America's Most Wanted's set resides in this tribute to the history of crime and punishment.

Fittingly, America's museum of architecture is itself a magnificently designed old building.

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.

A historic arena where the Beatles played their first concert in the U.S.

The grand marble structure next to the White House is Andrew Carnegie's temple to Pan-American diplomacy.

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

The beloved statue at the National Academy of Sciences is oh so inviting to sit on.

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

D.C.'s first central library was born out of a chance encounter with the philanthropist whose name it bears.

The bank that helped fund the Mexican-American War and the purchase of Alaska met its downfall after helping Augusto Pinochet launder money.

The national park was once a plantation estate.

The first purpose-built art gallery in the United States is once again open as a center of craft arts.