One of the Seven Wonders of the Modern World holds the world's tallest metal staircase.

A 98-room castle in the middle of Toronto that bankrupted a 19th century electricity multimillionaire.

The palatial McDonald's that inspired Wesley Willis.

Chicago's Navy Pier on Lake Michigan was a training hub for aircraft carrier pilots during WWII.

Four glass boxes hover over 1,000 feet in the air to give visitors an unparalleled view of Chicago.

The most confusing clock in New York.

A pedestrian island in the middle of world-famous Times Square emits a strange (and purposeful) humming noise.

These unusual rooms on wheels are holdovers from the 1960s.

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

The naval commander’s proudest moment in battle is memorialized in this unique tomb at Arlington Cemetery.

Born a slave on the Arlington estate, Parks dug the first graves at Arlington National Cemetery, and was buried there, too.

The final resting place of an unidentified revolutionary soldier sits behind a Virginia church.

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

The controversial urban planner who designed Washington, D.C., was buried in Maryland, and can presently be found in Virginia.

At Washington's Dulles Airport is a satellite museum (no pun intended) with three quarters of a million square feet of aircraft history.

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

The only place for a truly presidential dram.

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

An extensive, if one-sided, history of U.S. law enforcement's war on drugs.

At 207 feet, one of the world's longest continuous escalators.

This Virginia railway overpass is said to be haunted by a serial killer in a rabbit costume.

FDR's Art Deco hospital tower was hopelessly inefficient.

This massive swimming pool is the high tech home to the human-powered submarine races.

This bug-eyed water wheel uses the power of the Sun to clean up Baltimore Harbor.