A building shaped like the Army Corps of Engineers logo, because why not?

Walk a trail through a historic Quaker town that outlawed slavery in 1777 and was a major waypoint on the Underground Railroad.

Brain collection and database that narrows the gap between man and animal.

The only Civil War battle in Washington D.C. took place near this highest natural point in the city.

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

Enormous piles of historically significant stones, dumped by Congress in a forest, and abandoned for 60 years.

A Civil War fort in the middle of Washington, D.C. has been swallowed by a forest.

The span is crooked and made from two older recycled bridges.

Built by the patriotic residents of Boonsboro in a single day.

A cave on the Maryland border where civilians took refuge during the bloodiest battle of the Civil War.

A monument marks the location of the first successful steamboat demonstration.

A lone historical marker off the highway and scattered debris are all that remain of this Cold War-era missile site.

Three abandoned missile silos are hiding in plain sight behind a suburban development in Maryland.

Volcanic stone sentinels stand watch at a Korean Bell Garden in Virginia.

This pre-Revolutionary War grist mill ground corn and flour for soldiers in seven American wars.

The ruins of this long-abandoned unsuccessful gold mine can still be found.

This advertisement for talcum powder was painted on the rock face and has since defied removal.

This former Cold War missile control site played an important role in the creation of GPS.

An out-of-place Air Force radar dome is all that denotes this park as a former missile launch site.

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

This abandoned Victorian-style house was built in 1884.

A decaying garage hidden amid the dense forest is all that remains of a once-prosperous dairy farm.