This seemingly out-of-place gas station by the Watergate hotel was once described as the most expensive gas station in the world.

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

Helen Keller once broke ground on this historic center for the study of technologies to benefit the hearing impaired.

A muscular Art Deco monument represents the struggle between regulators and unbridled markets.

A building shaped like the Army Corps of Engineers logo, because why not?

Washington's top-secret Cold War-era doomsday communications tower is located in a small neighborhood park.

Before Nixon, "watergate" meant canals.

A much-maligned monument to teetotalism.

A historic arena where the Beatles played their first concert in the U.S.

A derelict bit of transportation infrastructure hidden in the woods.

This narrow coastline trail through the dense Kauai wilderness is among the most beautiful and dangerous in the world.

Tucked away in the Tower of London is the weapon once used to execute high-profile prisoners.

The watery entrance for condemned prisoners heading to the Tower of London is still visible along the Thames.

High atop the Eiffel Tower is a small apartment built exclusively to entertain the science elite and make the rest of Paris jealous.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

No telescopes, no power, no gift shop: The Observatory of Chichen Itza, one of the world's oldest observatories, takes astronomy back to basics.

A small collection of iguana-infested ruins hides amid Cancún's bustling hotel zone.

Clap your hands at the base of the pyramid, and the song of a sacred Mayan bird will echo through the air.

Every equinox this Maya pyramid puts on a spooky ancient light show.

Central America's deepest lake is actually a volcanic caldera, surrounded by three volcanoes.

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

This lovely picnic spot featuring thunderous jet landings is an aircraft spotter’s dream.

Thomas Jefferson's estate is home to hundreds of varieties of historic fruits and vegetables.

This stately building in Alexandria, Virginia was built by Freemasons to honor one of their most famous members.