A building so large that it has its own weather.

The walls of America's oldest masonry fort famously "swallowed" cannonballs.

An 18th-century Spanish watchtower made entirely of seashell and concrete.

A monument celebrating the idea of reaching inaccessible places.

In the depths of the Everglades, one man has dedicated his life to studying the elusive Skunk Ape.

Florida's oldest bar was once a morgue, complete with a hanging tree and gravestones.

A tribute to Ponce de Leon's supposed quest for eternal youth.

Here’s how Robert the Doll earned his reputation as the most haunted doll in the world.

The former home of the Nobel Prize-winning American writer is now home to dozens of six-toed cats.

These remote Florida islands have a history of sea turtles and sunken treasures, and one of the world’s largest coastal brick fortresses.

The former home of the "Father of Black History"

This American Civil War-era fort still stands near the border between Washington, D.C. and Maryland.

Engraved in stone here are the signatures of everyone who signed the Declaration of Independence.

Ruins from the Parthenon and petrified wood line the interior of one of the world's most famous monuments.

This bridge over D.C.'s Rock Creek Park is sometimes called the "Buffalo Bridge" because of its four buffalo sculptures, which were cast from a single piece of bronze.

The Lincoln Memorial has inspired many, even though a word on the inscription appears to be spelled incorrectly.

On the Fourth of July this area will transform into a Pompeii-like storm of falling embers and ash.

One critic described it as "middle Mussolini, early Ramses, and late Neiman-Marcus." Another called it an architectural "natural disaster."

The final residence of an educator, civil rights leader, and presidential advisor was also the first headquarters of the National Council of Negro Women.

The 5.5-mile ring of steel posts around the Capitol Building is one of the largest (and most uniform) of its kind in the world.

A 1,100-ton train fell through the floor in 1953. Workers got it patched up in just 72 hours.

A derelict bit of infrastructure from the canal that once ran through D.C. is landlocked in the heart of the city.

A hidden passageway now marks the site of an assassination attempt on Ronald Reagan that some say broke a 140-year-old curse.

An overlooked memorial honoring the local Washington residents who died in World War I.