North America's oldest quarantine facility was built in response to Philadelphia's 1793 yellow fever outbreak.

Step into a pastel time capsule where candy is truly dandy.

Amid the bustle and noise of the Financial District hides a secluded garden oasis above the city streets.

An abandoned subway tunnel that could have reinvigorated Staten Island still lies somewhere beneath this Brooklyn park.

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

This Delaware River bridge is emblazoned with a catty slogan from a more prosperous time.

This tiny structure was built by the creator of the Brooklyn Bridge.

Pennsylvanian mass grave and possibly mass murder.

This hospital fell into ruins after failing to act as the advocate for the mentally ill it was designed to be.

Hundreds of glow-in-the-dark objects light up a museum in a historic zinc mine.

This stone tower marks a lookout point over the historic Washington Crossing, and maybe some buried treasure.

An extraordinary collection of vampire-themed antiques lurks on the second floor of a store.

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

A modern ghost town whose inhabitants were driven away by the growth of nuclear power.

New Jersey's last historic covered bridge was rebuilt from pieces of the original 19th-century structure.

Inside this 150-year-old barn turned antique shop is a vast array of items for curios hunters.

Mysterious rocks that ring musically when struck.

A "house to which to flee" for settlers in colonial Pennsylvania.

In which a local geological marvel becomes a quaint roadside attraction.

Once the world's largest reinforced concrete structure, this abandoned bridge now beckons urban explorers.

A toxic ghost town sitting atop a massive coal fire.

The only geyser in the state of Pennsylvania is caused by pressure from an abandoned coal mine outside of the ghost town Centralia.

A mine fire has been burning under the deserted town since 1962, but this church is still going strong.

This huge, disused viaduct is now a crumbling concrete underworld of covered in years of graffiti.