The world's longest known cave system.

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

Named for a prominent scout and explorer, this Wyoming state park encompasses a replica of an 1840s trading post, a 19th-century Army outpost, and early 20th-century automobile lodgings.

This impressive working clock made of 16,000 plants changes its flowers twice a year.

This historic Victorian hotel has a scandalous history of affairs and murder.

Legend says one of the world's largest marine geysers is actually a whale that got wedged within the rocks.

A 19th-century Baja cantina that many say is the birthplace of the margarita.

Oldest existing church in New York and the inspiration for Washington Irving's "The Legend of Sleepy Hollow."

The huge granite obelisk that towers over a small California town.

Bits and pieces from the ill-fated Donner Party's winter cabins.

A replica of the first public theater built in California.

The California capital city once stood 10 feet lower than it does today.