A six-story treehouse offers spectacular views of New York's Finger Lakes region.

A careful eye can find hundreds of dinosaur tracks running along the Connecticut River.

The abandoned ruins of America's first private zoo are open for exploration in the Catskills.

The ruins of this Thomas-Jefferson-designed mansion have been left to crumble since the Christmas Day they burnt down.

The world's longest known cave system.

This grave marks the final resting place of pioneer John Chapman, better known as Johnny Appleseed.

This maze-like slot canyon is a unique gem within an already fascinating geological area.

Astounding collection of coin-operated games and automata.

Advice-columnist's bell tower, paid for with pennies.

The bones of an old zoo crumbling in the shadow of a new one.

The only surviving prototype for Buckminster Fuller's house of the future.

A medical facility that has been kept frozen in time.

Lions and tigers and leopards, servals, pumas, bobcats, lynxes, and ocelots... oh my!

Dedicated to the art and science of glass in equal measure, this space is as much laboratory as museum.

This peaceful gem in upstate New York was chosen as the future home of the 14th Dalai Lama's Library and Museum.

One of nature's most well-scheduled phenomenons resides in Wyoming's Yellowstone National Park.

The residents at this Yellowstone wildlife park will certify your cooler as "bear-proof."

Offering commanding views of the California coastline, this restaurant was a hub for the artists and bohemians of Big Sur.

It's not your typical library, memorial, or book store.

The world's largest military aircraft cemetery.

An eccentric inventor's castle home with its own indoor weather system.

Experience the hysteria of a 17th century witch hunt through goofy reenactments and wax dummies that should probably be burned at the stake.

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

The only structure left with direct ties to the Salem witchcraft trials of 1692.