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

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

The only sea in the world that has no land boundary.

Be(w)ar(e) the moat around this historic Czech castle.

The largest piece of no man's land left on Earth.

Look closely and you’ll notice that the color changes a third of the way up the tower.

The second oldest Jewish graveyard in the U.S. is tiny, with connections to George Washington and Henry Wadsworth Longfellow.

A line of blue paint marks the route of the inaugural parade.

These giant volcano sponges in Antarctica are thought to be the world's oldest living animal, at 15,000 years old.

This historic steamboat is scuttled just a few hundred feet from where it was built over a hundred years ago.

The internal railway of one of the biggest steel plants in America has been transformed into a linear park with unique industrial views.

A daybeacon pyramid is about all that's left of this island that is said to have sunk due to a pirate's curse.

One tiny triangular park commemorates the victims of a yellow fever epidemic—many of whom are buried right below the grass.

A former connection to City Island, it has been abandoned since the 1930s.

Descend 2,030 years into the past in an ancient tunnel built to support Jerusalem's most famous wall.

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

The only known Futuro house in North Carolina sits along a stretch of desolate highway on the Outer Banks.  .

A stone slab in Madrid marks the point from which the distances of Spain's national roads are measured.

The mysterious large white cross visible from the runway is a memorial to a massacre during Spanish Civil War.

Death rituals and sacrifice inside a Peruvian megalith.

The oldest garden in Prague, once part of an medieval orchard.

This mysterious structure by the Washington Monument is a flood barrier designed to protect the White House against rising waters.

Around 100,000 bodies are buried below the medieval headstones, many of which mark graves with multiple bodies stacked up to 12 deep.

This abandoned lighthouse looks like a rusting oil rig, but has managed to survive a number of storms.