Legend has it that President Grant’s frequent drinking in the lobby gave rise to the term “lobbyist.”

An Industrial Revolution-era public work that purified water using nothing but sand.

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

A historic estate packed with George Washington's heirlooms, and its own nuclear bunker.

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

An innovative attempt to break a siege in the American Civil War still scars the earth today.

The eerie ruins of a remote abandoned hamlet said to be founded by the survivors of a shipwreck.

A bunker "with enough U.S. currency to replenish the cash supply east of the Mississippi" in the event of nuclear war now protects nitrate film.

This sprawling museum holds one man's giant collection of real tanks.

This maze-like slot canyon is a unique gem within an already fascinating geological area.

An alternate history park where the Union Army loses the war... to dinosaurs.

A railroad tunnel that, upon its completion, was considered one of the engineering marvels of the modern world.

A secretive collection featuring objects that were designed specifically for U.S. intelligence operations.

A 300-yard long natural tunnel runs through a ridge deep in the Appalachian Mountains.

Giant busts of 42 U.S. presidents are sitting in a field in Virginia.

A sacred site for Native Americans surveyed by George Washington and owned by both King George III and Thomas Jefferson.

The only recreation of William Shakespeare's indoor playhouse.

The remains of a community that was forced to move for a dam that never materialized still rot in this Pennsylvania park.

The wooden octagon in which Huckleberry Finn and A Connecticut Yankee were born can still be visited in upstate New York.

The origin of this mechanical boy was a mystery until he revealed his maker by writing it in perfect cursive.

The house that Frank Lloyd Wright "(shook) out of his sleeve at will" at the age of 86.

Over 100 concrete munitions bunkers are all that remain of a Pennsylvanian village seized by the US government.

Sail through this subterranean show cave that is home to a legend that would go on to name nearly everything around it.

Edgar Allan Poe's old dorm is now a shrine to the author's legacy.