The 5.5-mile ring of steel posts around the Capitol Building is one of the largest (and most uniform) of its kind in the world.

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

Daredevil repair workers can worm their way out the access hatch, loop ropes over the apex and rappel down the monument.

100 years later, they're still down there.

There's an old indoor swimming pool hidden directly underneath the White House Press Briefing Room.

The monument's pointy aluminum tip has been melted down by repeated lightning strikes.

The first presidential bomb shelter was located in an old vault under the Treasury, connected to the White House via tunnel.

The "lovely red Vega" of the legendary record-settling pilot.

Those with a sharp eye can find the hidden image of a German Shepherd on the memorial's Mural Wall.

The actual model from the original "Star Trek" series is now on display at the National Air and Space Museum.

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

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

Sniff the Titan Arum's rotting flesh.

A Victorian cemetery in the heart of Brooklyn remains a popular mecca of morbid curiosity.

A way to take your secrets to someone else's grave.

A tree that grows parallel to the ground was declared Brooklyn's "crowning curio" by the poet who saved it.

This city park was once a lookout point for George Washington’s army during the Battle of Brooklyn in 1776.

Michael Jackson got Bad and Crocodile Dundee walked on heads in this iconic Brooklyn subway station.

A gothic church spire sits atop this skyscraper, the tallest church in the world.

The body of at least one victim of a construction accident was left behind in the collapsed pylon, buried under tons of concrete.

These chunky stone towers out in Lake Michigan are the key to Chicago’s drinking water.

A 400-foot-tall tall map of Chicago makes this once-ignored building stand out.

The twin towers in this Chicago fountain use 50 foot tall video screens to spit on people.

The only Bahá'í house of worship in North America and one of only a handful worldwide.