While most wind tunnels test scale models, the "Cave of Winds" was large enough for actual airplanes.

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

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

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

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

The national park was once a plantation estate.

This lonely waterfront memorial to the men of the Titanic was erected by the "Women of America."

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

The first partially complete dinosaur skeleton was discovered here, forever changing the world's view of the ruling reptiles.

Destructive children, start your engines.

Now abandoned, the first public health hospital in the U.S. saw more than one million immigrants from around the world.

Step inside Lucy, the world's largest "elephant."

The site of one of history's most indelible and horrific tragedies.

Hidden in plain sight on the Hudson River is an abandoned train station where nature has taken over.

This outdoor gallery of graffiti-covered walls pays homage to the past, present, and possible future of street art.

This historic address is home to the beloved ball and is an almost totally empty building among the most expensive real estate in the world.

An oasis of calm amid the chaos of the boardwalk, the museum traces the heritage of this beloved beachside amusement park.

One of the most enjoyable bits of history at Coney Island and “the most romantic ride in the world.”

This Philly landmark has a giant butterfly pavilion, three floors of insect displays, and withstood a $40,000 heist.

Yo, Adrian!

This Philly cemetery is the eternal home of many famous area residents, including Rocky Balboa's wife.

This beloved marketplace mascot poops money and grants good luck.

The last of Philadelphia's wood-paved streets is now a landmark of terrible engineering.

This elaborate towering structure was once famed for its revolutionary height.