This spot in St. Louis, marked with a simple sign, has seen more pro baseball than just about anywhere else in the world.

Maryland's first (and last standing) toll house on America's first federal road established the state as the "Gateway to the West."

This nine-story building is the oldest standing skyscraper in D.C.

The modest childhood home where the baseball legend and Yankees star learned to hit from both sides of the plate.

A sculpture made of 10 Cadillacs as a monument to the "Golden Age" of the American automobile.

This geothermal hot spring hides beneath a slowly growing mineral dome.

This grand gothic brewery has been pumping out suds for over a hundred years.

This rugged area of red rocks and arches is often considered one of the most beautiful places on Earth.

One man's ambition created this psychedelic log home.

A popular swimming hole that hides one of America's most deadly diving spots.

Abandoned bridge hidden deep in the San Gabriel Mountains.

This cemetery has graves dating back to the 17th century, including the city's oldest carved tombstone and an ominous cryptogram.

Here, at the "world's longest art gallery," you'll find forty miles of ancient petroglyphs and pictographs.

An acoustic anomaly with a mysterious cause.

Hollywood's most famous landmark, the "temporary" sign that has stood for decades longer than intended.

A religious-themed park filled with folk art to bring biblical stories to life that fell into disrepair and now being restored.

This secluded aqua waterfall in the Grand Canyon is the perfect swimming hole, and the Havasupai tribe's fiercely protected natural wonder.

An underwater city for the dead.

These remote Florida islands have a history of sea turtles and sunken treasures, and one of the world's largest coastal brick fortresses.

Manhattan’s Battery Park has a whimsical carousel full of spinning, glowing fish.

Collapsing castle on the Hudson river was once the storage site of military surplus business.

Towering basalt columns, a creation of fire and ice.

The seamy, underground secrets of Portland's criminal past.

A hand-built folk art installation covered with messages of God's love.