A former insane asylum despised by Nelly Bly and Charles Dickens is now fashionable apartments.

Site of the first pathological and bacteriological research facility in the United States.

The feral felines of Roosevelt Island have a small army of allies and an abandoned hospital all to themselves.

A crumbling hospital from the 1850s on Roosevelt Island.

Waterway populated with abandoned projects, including a submarine.

This small, hidden cove is home to abandoned boats.

The childhood home of one of America's greatest unsung troubadours still stands in a much changed Brooklyn neighborhood.

Nondescript elevator doors open to reveal a stunning, surreal world.

Brooklyn's Barkaloo Cemetery is the resting place of a scant two bodies.

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

The rare American Civil War-era weapon was never fired in anger.

What was once a vast naval cemetery is now home to nesting birds and pollinating bees.

Look closely and you’ll notice that the color changes a third of the way up the tower.

One of the most influential presidents in U.S. history wanted only this plain, elegant monument as his lasting memorial.

The preamble to the U.S. Constitution written entirely from vanity license plates hangs in the Smithsonian museum.

The unique traffic pattern named for an influential urban planner is also known as the Pedestrian Scramble.

A traveling postal dog covered 48 states and more than 140,000 miles, and he lives on as taxidermy, patched up with a rabbit's foot and a pig's ear.

A 1,100-ton train fell through the floor in 1953. Workers got it patched up in just 72 hours.

Railroad officials in the early 1900s sought to spare travelers the sight of Roman soldiers’ private parts.

This once-grand marvel of engineering is now 41 miles of scenic hiking trail.

The home of aviation trailblazers, in a remote corner of the big city.

These falls, sometimes called the "Niagara of the West," still put on a good show at the right time of year.

The largest outdoor art gallery in the Northwest United States.

Jail from the 19th century that was built by inmates.