Thomas Jefferson's estate is home to hundreds of varieties of historic fruits and vegetables.

An organ located deep within a cave, whose "pipes" are the geological features of the cave itself.

The longest and widest floating bridge in the world.

Spanning an elevation of 160 feet and containing 388 steps, this is Seattle's longest staircase.

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

Was there a small "backpack nuke" hidden in the attic? JFK apparently thought so.

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

Look closely and you’ll notice that the color changes a third of the way up the tower.

There’s a special club house at the top for the bell ringers.

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

Washington's iconic carousel has a nice piece of Civil Rights history.

Decades before the scandal, this staircase on the river was a literal "water gate."

A nostalgic bibliographic gem.

Cavernous opening completely encased in Karst limestone.

The oldest colonial fortress in the Americas was once the home and later prison of Christopher Columbus.

This small fort played a huge role defending Puerto Rico’s capital city.

This colorful gate stands as an entrance to the walled city of Old San Juan.

This chapel on a cliff is renowned for its healing powers and was founded on the site of a supposed divine intervention.

Legend tells how a Spanish soldier disappeared from this isolated sentry box without a trace.

Rumored to be the famed pirate's lookout tower, this historic stone structure is now just watching for tourists.

This elegant Colombian fortress was one of the torture headquarters for the Spanish Inquisition.

The only airport with a people mover system designed by Walt Disney Imagineering.

In Houston's airport, a cow is properly equipped to jump over the moon.

A few times a day, you can see an animatronic cowboy shoot-out.