It would take 35 firetrucks to fill this enormous glacial pothole.

This charming colonial alleyway is one of the oldest continuously used residential streets in the U.S.

A rare view of a preserved Victorian science museum.

Overshadowed by quilts, the artistry of these patterned textiles went underappreciated for too long.

This historic furnace was once used to produce cannonballs during the Civil War.

The only statue of its kind to commemorate Washington's beginnings as an officer of the British Colonial Militia.

Old neon signs from the City of Brotherly Love provide a snapshot of the city’s evolution.

A former plant in one of the hubs of U.S. steelmaking has been turned into this museum celebrating the history of American industry.

One of the oldest surviving lock houses on the Ohio River.

A museum commemorating the Donora Smog, which killed 20 people in October 1948 and sparked national outrage over air pollution.

Dozens upon dozens of boulders engraved with scripture tell the story of one man's troubled life.

The home of possibly the least-loved U.S. president stands as a sort of unpopular Monticello.

America's smallest national park site is the former residence of exiled Polish national hero Thaddeus Kosciuszko.

A miniature golf course crafted inside the world's largest simulated cave.

A museum dedicated to the history & joys of the trail & your best chance to see hikers throwing up ice cream.

One of the U.S. Forest Service's only mansions is outfitted with a dinner table for floating food.

Contrary to what one might expect, ice forms inside this small cavern during the summer and melts during the winter.

Erected in 1697 this Philadelphia bridge is the oldest surviving roadway bridge and perhaps the oldest stone bridge in the United States.

This jail which was in service for over a century is now open for curious visitors.

The internal railway of one of the biggest steel plants in America has been transformed into a linear park with unique industrial views.

Tour the dark and beloved poet's former cobwebbed basement, which may have inspired "The Black Cat."

This train station inspired the name of a 1970's rock band and provided the backdrop for their album cover.

A lightship turned museum, outfitted with artifacts from the vessel's past as part of the U.S. Lighthouse Service.

The former home of the man whose radical ideas changed the nation.