This Industrial Age architectural and engineering gem helps visitors and residents alike traverse Lisbon, “The City of Seven Hills.”

Sip cherry liqueur at a bar dating back to 1840.

Maryland's first (and last standing) toll house on America's first federal road established the state as the "Gateway to the West."

Once home to seven different roller coasters, Glen Echo has undergone many transformations since its founding in 1891.

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

This small hilltop church weaves the urban history of Washington, D.C. with the national history of the United States.

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

A painfully obvious spy house sits right across the street from the Russian Embassy.

A brass and marble scale model of the solar system embedded in the concrete.

A bas relief commemorates the "Nuns of the Battlefield" who cared for soldiers on both sides of the conflict.

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

A small triangle of DC grass is the final resting place of one of Sonny and Cher's songs.

With over 100 jam-packed rooms to explore plus elaborate tea services and events, the Mansion on O Street is a hidden treasure.

The graveyard holding the remains of George Washington's slaves was forgotten for nearly 200 years.

This lovely pocket park is one of the most under appreciated in D.C.

The Pentagon is so large that it was planned like a city, complete with internal highway infrastructure.

There’s a hidden military meme engraved on the World War II Memorial.

An overlooked memorial honoring the local Washington residents who died in World War I.

The hidden offices underneath Memorial Bridge have been locked up since 1976.

The national park was once a plantation estate.

The winding route passes through an enclosed alleyway, two tunnels, and leads to the White House basement.

Nothing says indulgence like a 1,500-pound chocolate castle.

This abandoned dream castle and its cemetery look out over the city that once inspired their creation.

Step into the courtroom to learn details of the only case in history where ghostly testimony led to a murderer's conviction.