This ruined quarry once produced the distinctive red sandstone used for construction projects in Washington, D.C.

An old pay phone rewired to play local bird calls and songs at the press of a button.

This Asian-inspired tower in a lush urban park provides spectacular panoramic views of Baltimore.

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.

The ruins of an 18th-century mansion that was once named "Mistake" by the man who had it built.

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

The hidden ruins of a mill that is linked to an attempt to assassinate the vice president of the United States.

Remains of a historic fountain that was mysteriously lost in the demolition of a D.C. traffic circle.

A benevolent, 16-foot-tall river dragon lives on a suburban lawn.

Giant acorn-shaped 19th century gazebo from which suburban Washingtonians gazed upon the original "silver" spring.

A mammoth pair of Civil War artillery guns abandoned out in the forest.

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

A pre-Industrial Age iron furnace and the site of a nearly-forgotten piece of Black history.

A monumental statue of RCA's mascot now sits atop a historical society roof after a life of moving around.

A remote horde of architectural treasures fit for Indiana Jones.

This scenic Maryland park was the site of one of the worst prison camps of the Civil War.

This abandoned sea fort has become an accidental bird sanctuary.

Captain John Smith thought these cliffs were amazing in 1608 but sharks thought so 20 million years before him.

Once home to seven different roller coasters, Glen Echo has undergone many transformations since its founding in 1891.

After hundreds of years of settlement, this once-bustling fishing village sunk into the Chesapeake Bay.

This English-inspired Maryland garden is home to acres of opulent plant life including bushes shaped into an entire fox hunt.

Despite violent work crews and massive delays this abandoned canal tunnel was built to last into the modern day.

Once part of a dam servicing an early 19th century grist mill, the tucked-way falls are a tricky-to-find urban oasis.

This dig site outside D.C. is known for its exceptionally high density of baby dinosaur fossils and dinosaur eggs.