This estate on the banks of the James River was home to a Founding Father, two presidents, a famous bugle melody, and what some say was the actual first Thanksgiving.

A home built with marble tombstones from the graves of 2,200 Union soldiers buried in a Virginia cemetery.

A former mental hospital founded in the 1930s by a eugenicist who advocated for the forced sterilization of patients.

An autonomous oak in Alabama.

What else would you call a playground hidden in Alabama's oldest and largest cemetery?

This natural wonder drops 16 stories straight down through rare flora and streaming waterfalls.

One of the most poignant ruins of the Chernobyl nuclear disaster, the local football team's stadium has been quickly reclaimed by nature.

Thousands of fossilized footprints speckle this Bolivian national park.

One of the few places in the world where visitors can walk alongside fossilized tracks from 80 different dinosaur species.

On this stunning Scottish island, you can walk in the footsteps of dinosaurs.

One of the most extensive and well-preserved collections of dinosaur footprints in North America.

The meteor that sealed the fate of the dinosaurs landed at this site, one of the largest impact craters in the world.

This imposing Masonic temple a mile from the White House was the first public library in Washington, D.C.

Largest Roman Catholic church in North America.

Government testing at the asylum briefly explored using marijuana as a "truth serum" on Nazi prisoners of war.

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

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

A nostalgic bibliographic gem.

This stunning blue and gold room changed cities twice before becoming part of the Smithsonian.

Fittingly, America's museum of architecture is itself a magnificently designed old building.

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

This lonely waterfront memorial to the men of the Titanic was erected by the "Women of America."

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

A wondrous old library overlooking the nation's capital.