The oldest continuously operating fish market in the United States.

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

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

Largest Roman Catholic church in North America.

Franciscan monks created a facsimile of the Holy Land for North Americans who couldn’t afford the trip overseas.

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

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

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

Home to items never before seen by the public.

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

This bug-eyed water wheel uses the power of the Sun to clean up Baltimore Harbor.

A relic of FDR's brief foray into utopian urban planning.

This former asylum for Black Americans is haunted by its history of violence and racism.

Rediscovered after a century, the father of the American Navy was reinterred in something dredged up from Davy Jones' Locker.