This nine-story building is the oldest standing skyscraper in D.C.

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

When it comes to handsignals (and colonialism) rock always beats scissors.

When it opened during the final years of the embargo, all the drinks and cigars were free.

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

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

An atomic bomb-proof strongbox protects the U.S. Constitution from terrorists and thieves.

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

The walls of the iconic dome are hollow and have a secret stairway.

This imposing Masonic temple a mile from the White House was the first public library in Washington, D.C.

Largest Roman Catholic church in North America.

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

Home to items never before seen by the public.

This grand gothic brewery has been pumping out suds for over a hundred years.

A tiny piece of the Moon is embedded in this stained glass masterpiece.

A layered tribute to the work of mosaicist Isaiah Zagar.

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

Yo, Adrian!

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

This ancient Roman bridge and aqueduct still stands as a wonder of classical construction.

The world's tallest bridge is also possibly the most elegant.

A daring D-Day assault by U.S. Army Rangers is commemorated atop the high cliffs of this strategic point.

A memorial to the nearly 10,000 American soldiers laid to rest on the beaches of Normandy during WWII.

The opulent home that inspired Tintin's Marlinspike Hall and the adventures within.