One of two lighted lanterns hung in the church belfry on the eve of the Revolutionary War to warn that the British were on their way.

Home to the largest urban bat colony in North America, estimated at 1.5 million bats.

One of the indelible moments of the American Revolution took place at this location.

Site of a famous 19th-century transcendentalist utopian community, now abandoned.

The Boston square dedicated to the dark poet who was born nearby.

The oldest Italian café in Boston, this spot also serves as a veritable museum of vintage coffee ephemera.

A beautiful Victorian-era cemetery, complete with a miniature village.

"Congress may voluntarily remain in session throughout the summer, in order that our Congressmen may be protected from the intolerable discomforts and dangers of the ordinary outdoor weather!”

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

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

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

100 years later, they're still down there.

Before Nixon, "watergate" meant canals.

A historic estate packed with George Washington's heirlooms, and its own nuclear bunker.

The Byzantine, pre-Columbian, and medieval art at this stately mansion are some of the most under-appreciated collections 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.

The sci-fi villain is a little-known inhabitant of the U.S. capital's largest cathedral.

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

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

The United States Capitol's former columns still stand.

The romance of early commercial flight still fills this Art Deco destination.

This isn't your average roadway—it's actually a National Park and a transportation pioneer.

The remains of a historic plantation nestled in between a parking lot and the rental car return at Reagan National Airport.

This historic hotel on Bathhouse Row in Hot Springs National Park has a storied history of gangsters and baseball greats.