The "Seinfeld" diner.

The angel of death appears to weep black tears at this grave marker.

This serene oasis in an affluent Los Angeles neighborhood holds some of Gandhi's ashes and got Elvis into Eastern Philosophy.

The abandoned husk of a mental institution that failed to save a Jazz Age icon still sits nearly unchanged.

The largest earthwork effigy in the world.

Breathtakingly blue walls shimmer inside the "Glacier Behind the Town."

Frank Lloyd Wright's most iconic home dangles over a Pennsylvania waterfall.

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

Carved by a waterfall in a hard-to-reach rock formation, this heart-shaped rock has inspired romantics for decades.

A celebration of capitalism in Midtown.

It's not hard to see why the historic Peabody Conservatory of Music's library has been described as a "cathedral of books."

An acoustic anomaly with a mysterious cause.

Ride the subways of yesteryear.

A three-story copper skybridge connects two Manhattan buildings with Art Deco luxury.

Ninety feet off the valley floor is an ancient dwelling put under protection of the U.S. government by Teddy Roosevelt.

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

The oldest surviving bridge in New York City, which reopened to pedestrians in 2015.

The world's longest known cave system.

A legendary speakeasy bookstore returns from the brink.

The second-largest cave chamber in the world was discovered in 1898 by a 16-year-old and a friend known as "Pothead."

Hidden in an ordinary Midtown building is a one-room museum dedicated to the greatest escape artist.

Take a drunken tour inside the world's largest known geode.

The largest hot spring in the United States is, as the name suggests, a stunning show of natural color.

The hike through a narrow river flanked by the 2,000-foot-tall walls of Zion Canyon is one of the best in the world.