Hidden within an idyllic suburban garden is a memorial dedicated to the victims of a terrifying spree of killings committed on U.S. soil.

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

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

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

This abandoned Victorian-style house was built in 1884.

A grassroots community effort in the 1970s led to the creation of this beautiful garden full of delightfully whimsical exhibits.

It's not hard to see why the historic Peabody Conservatory of Music's library has been described as a "cathedral of books."

A hidden alley in urban Baltimore is a haven for graffiti artists.

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

The Byzantine, pre-Columbian, and medieval art at this stately mansion are some of the most under-appreciated collections in D.C.

A girls' boarding school inspired by the Chicago World's Fair, once abandoned, now restored to strange and scenic glory.

At 207 feet, one of the world's longest continuous escalators.

Once a sewer culvert, this road tunnel now offers cyclists and pedestrians a subterranean stroll under the C&O Canal.

A derelict bit of transportation infrastructure hidden in the woods.

The tallest The Church of Jesus Christ of Latter-day Saints temple in the world soars above the Beltway.

An intricately designed junk art house with four extravagant junk art cars hidden in the suburbs.

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

Art deco landmark on the outskirts of Washington, D.C.

A lovely aquatic park built by a one-armed Civil War veteran who made a fortune from lotuses.

A haunting tribute to pioneering photographer Clover Adams.

This abandoned asylum was once a state of the art facility before devolving into one of the most deadly mental institutions in American history.

This Maryland farm is known for its amazing corn mazes and its 30-foot junkbots.

This palatial botanical garden is home to one of the largest pipe organs ever installed in a private residence, and a piece of Wood's cycad.

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