The design of this historic domed church was influenced by Thomas Jefferson and intended as a statement of religious freedom.

The longest escalator in the Western Hemisphere takes over three minutes to ride down.

A faded sign from the 1920s remembers Baltimore's resistance toward banning alcohol.

This dig site outside D.C. is known for its exceptionally high density of baby dinosaur fossils and dinosaur eggs.

A 200-year-old bar with a cheeky name claims to have served Edgar Allan Poe his final drink.

The trials and tribulations of marking Poe's grave.

The world's oldest soul food restaurant is also one of its best.

A tiny monument to the unsuccessful attempt by Thomas Jefferson to place the prime meridian in Washington.

Go take a picture with the inventor of the daguerreotype photographic process.

Senators used to relax in the nearly forgotten marble tubs now hidden in the U.S. Capitol Building's basement.

Washington's iconic carousel has a nice piece of Civil Rights history.

The most accurate timepiece in the world.

The oldest building in the District of Columbia was preserved because of a mistaken connection to George Washington.

Rumor has it the uncarved lump behind the three famous suffragists is reserved for the first woman president.

Home to a vast and influential collection of Shakespeareana.

A super-sized promotional trick that is now a D.C. landmark.

The house where John Wilkes Booth conspired with his co-conspirators.

Largest Roman Catholic church in North America.

There's a crumbling old mansion inside the Smithsonian National Zoo.

This leafy estate is worth $18 million and is so grand it has two mailing addresses.

An obscure public service from the U.S. government that redeems burnt, moldy, and soiled old greenbacks.

A nostalgic bibliographic gem.

The national park was once a plantation estate.

An Industrial Revolution-era public work that purified water using nothing but sand.