Bad farming practices caused this unnatural natural wonder.

One of the largest-ever mental hospitals now sits abandoned, surrounded by 25,000 unmarked graves.

They call this long foot bridge a swinging bridge, but really it's the bouncing you have to watch out for.

An underground magnet for ever-changing street art.

Crumbling ruins mark the site of a couple's grisly murder in the woods.

Just a few miles from downtown Atlanta is a trail covered in a crazy collection of outsider art.

This demolished goliath of American industry once loomed over the depressed town it once made thrive.

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

Arlington Cemetery exhibit dedicated to death and grieving.

Century-old shop, specializing in Occult products.

An unusual and eclectic collection of local historical memorabilia.

Francis Julius LeMoyne built this crematory in 1876; he was the third person to be cremated here.

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

One Pittsburgh musician's decades-in-the-making memorabilia collection is on display at this rock-n-roll curio shop.

A unique workspace where offices reside on pirate ships and inside gingerbread houses.

This extraordinary Depression-era expenditure was modeled after a postcard of a Mediterranean hotel.

Journey through a collection of over 35,000 Halloween items from all generations.

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

Hidden behind West Philadelphia rowhomes is a haven for migratory and local bird species both ordinary and rare.

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

For decades, it has disappeared and reappeared as water levels rise and fall.

A rock maze opens up to a panoramic viewpoint at an abandoned mine full of ghost stories.

Descendants of this colonial Pennsylvania family still travel from far and wide to visit the 300-year-old home of their Quaker ancestors.

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