Golden Gate Park's historic collection of plants.

The 340-year-old house that inspired the classic Nathaniel Hawthorne novel.

An uber-secure, windowless tower of doom in the center of Manhattan is an NSA spyscraper.

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

The enormous 250-room Vanderbilt mansion conceals hidden doors and secret passageways.

This massive redwood tree has a hole in the base big enough to drive through.

This replica of the Greek structure is in the heart of Nashville.

By day this New Orleans square is for pedestrians, but by night it is a kingdom of kittens.

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

Gnarled canopies of pink and purple wildflowers arch over the trail to the summit.

Macabre headstones carved with winged skulls, dancing skeletons, and pithy reminders of impending death.

A luxurious 1880s hotel with its fair share of Tiffany stained glass, Edison electricity, and of course, ghosts.

Who needs fancy modern water slides when this giant North Carolina rock works just as well?

Arrr! The most authentic collection of pirate artifacts in the world... matey.

This Florida sinkhole hides a rainforest-like micro-environment in its depths.

New Orleans' famous cemetery, located on the site of a former race track.

Less a museum than a bizarre fantasy world created by artists and engineers.

A collection of 20th-century automata, penny arcade games, and musical contraptions.

One of the most scenic stretches of road in America winds between some of the country's oldest trees.

Quite simply the largest tree in the world (by volume).

Welcome to old Florida, where a 1940s mermaid show is still enchanting visitors.

San Francisco's newly reopened hands-on science museum.

This historic "City of the Dead" lies prominently in the center of New Orleans' famous Garden District.

This whimsical group of statues is a favorite of children who love to climb all over Lewis Carroll's beloved characters.