Every Christmas, one Arizona city makes the most of its dry climate by creating an arid desert tannenbaum.

This giant steer-skull edifice refuses to die.

Upside-down trees serve as natural flower pots in this hanging garden of Alaska.

Alabama has a fiberglass Stonehenge. With apologies to Spinal Tap, this one is full-size.

A small triangle of DC grass is the final resting place of one of Sonny and Cher's songs.

Art deco landmark on the outskirts of Washington, D.C.

The country's oldest continually-operated mini golf course lies hidden in plain sight, eclipsed by one of D.C.'s most popular tourist attractions.

A hidden gem on the lawn of the U.S. Capitol Building designed by landscape architect Frederick Law Olmsted.

This sculpture by artist Fritz Keonig survived the 9/11 attacks and now stands as a monument to the victims.

Visit the site of a subway powered by nothing more than air--and lots of it.

The beautiful tunnel that ran from the lobby to Penn Station is still hidden underneath 34th Street.

Cryptic messages embedded in the New York City sidewalk.

Wall Street has a new heroine, a bronze statue of a small but fierce girl.

Wine bottle sculpture with a ship's stateroom inside.

A clock set into the concrete outside a Manhattan jeweler has been telling time underfoot for over a century.

This elaborate towering structure was once famed for its revolutionary height.

This park contains a number of standing stones meant to heal and inspire.

Board a mine car and descend the #190 slope 300 feet underground into the Clark Vein of coal.

The Pennsylvania landscape depicted by a quarter mile of mosaics made from used road signs.

The oldest farmer's market in America is so ancient it was approved by the King of England.

Sail through this subterranean show cave that is home to a legend that would go on to name nearly everything around it.

Huge masonic hall in Philadelphia with lavishly themed rooms.

A toxic ghost town sitting atop a massive coal fire.

These tourist trap caverns are said to be the former home of a legendary Pennsylvania Hermit.