This stretch of the ancient Roman road is preserved in a valley that witnessed many battles and legendary highwaymen.

An abandoned stretch of highway, deteriorating next to the operational one.

Before Metro, Washington had a robust streetcar network—and you see the remains of this infrastructure if you know where to look.

Fittingly, America's museum of architecture is itself a magnificently designed old building.

A derelict bit of transportation infrastructure hidden in the woods.

The largest university building in the West is a gothic masterpiece containing dozens of theme rooms based on different countries.

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

A clone-tree in Washington Square Park sprung from seeds that went to the Moon and back.

One of Philadelphia's largest murals resides hidden under this bridge.

An abandoned cemetery lies in ruins as the surrounding forest swallows it whole.

America's most famous museum of medical oddities is home to the remains of Albert Einstein's brain.

This imposing Masonic temple a mile from the White House was the first public library in Washington, D.C.

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

Franciscan monks created a facsimile of the Holy Land for North Americans who couldn’t afford the trip overseas.