One man's swirling six-acre monument of stone.

This old cement mine has been used as everything from a mushroom farm to a recording studio.

For over 80 years, Mayan ruins stood proudly in a most unlikely location.

An unassuming island in the middle of the Hudson that hosts campers, including Aleister Crowley.

The life of one of FDR's possible mistresses is preserved in her palatial Hudson Valley mansion.

A granite monument honors a beloved World War II canine mascot.

The final resting place of a famous 19th-century murder victim whose identity is still a mystery.

Seven golden statues rise into the sky from sculptor Victor Victori's New Jersey front lawn.

The highest point in New Jersey is marked by a massive, if simply named, obelisk.

Local lore claims this park is named after a young woman who jumped off a cliff.

Several times a year, during low tide, two pairs of historic train tracks are revealed on this New Jersey beach.

The boulder on which Alexander Hamilton laid his head as he died can still be visited on the New Jersey coast.

A world-class collection of mechanical musical instruments and automata.

This massive boulder is either a unique rock formation created by glacial melt or a magic energy vortex.

The remains of a 19th century spring, and the site of an infamous unsolved murder.

One of the oldest anatomical theaters in the U.S. still in use was once the site of an infamous cadaver riot.

Ship skeletons haunt Baltimore's waterways.

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

The world's third-largest crystal sphere has sat in the Penn Museum since 1927 with the exception of one outlandish theft.

A daily replay of the experiment that proved the rotation of the Earth.

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

This meticulously extracted nervous system allegedly came from a 19th-century custodian who donated her body to science.

The oldest surviving botanic garden in the United States.

A museum dedicated to the strange and extravagant costumes and memorabilia of the mummers, a tradition older than Philadelphia itself.