The ruins of an old mill lie in a small ravine along a hiking trail near Little Seneca Creek.

The longest-covered bridge in the state of Maryland.

One of the earliest and best-preserved buildings in Charles County, Maryland.

First built around 1848, this bridge was destroyed by arson, but original timbers are included in the replacement.

This hidden treasure provides a charming access point along the south side of Baker Park.

Washed out by the Johnstown Flood in 1889, the surviving portion of the original two-span bridge now resides at Fishing Creek.

The smallest covered bridge in Maryland.

Built in 1815, the stabilized ruins of the grist mill and sawmill are now gated, but interpretive displays on the features and functions of the mill preserve its history.

Unannounced visitors are now welcome at the site of the largest Prohibition-era bootlegging operation in the region.

Explore the legends surrounding these mythical sea creatures inside this museum.

This beautiful stone arch bridge wasn't even expected to stand for one day, but people have been crossing it for centuries.

The remains of a chapel created for convenience.

An old abandoned mining town in The Adirondacks where Theodore Roosevelt first learned of the shooting of President William McKinley.

Abandoned 19th century homes once occupied by naval officers, soon to be demolished.

Toxic waste disaster that founded the Superfund program.

A theme park that suffered massive flooding during Katrina was abandoned, and now proves irresistible to trespassing explorers.

Beneath the mossy overgrowth covering this once-sprawling campus lies decades of history and the secrets that come with it.

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

An abandoned aircraft sits submerged in a lake in the Alaska wilderness.

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

A once grand hotel is being retaken by the wilderness it once capitalized on.

This abandoned amusement park was built on a site with a dark history.

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

Buildings that dynamite couldn't bring down were abandoned because of bathroom issues.