The only natural lake in the world that drains into both the Atlantic and Pacific Oceans.

An architect's childhood fantasy treehouse made real.

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

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

A beautiful geyser under environmental threat.

The first declared National Monument in the United States.

Tucked away on a scenic trail, a modest memorial honors one of the greatest writers of our time.

The world's first nuclear power plant is open to visitors looking to role-play a meltdown.

Despite his legacy of work in Spain, Cuba, and Florida, the larger-than-life writer's grave is a simple affair tucked in an Idaho cemetery.

Home to the deepest rift anywhere on Earth.

This quiet park's strange sedimentary spires were named after Kodak's color film.

Despite its name, this route in southern Utah offers a heavenly day trip.

The largest island on the great salt lake is home to curious creatures and strange stories.

An earthwork sculpture built by Robert Smithson in the Great Salt Lake only reemerges during drought.

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

Giant, natural amphitheaters made of delicate geological formations called "hoodoos."

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.

The last of Philadelphia's wood-paved streets is now a landmark of terrible engineering.

Golden and naked, the figure that was once the highest point in New York is all that remains of the second Madison Square Garden.

A tour de force of a fountain, memorializing a man who loved fountains more than anything else.

An Irish Memorial commemorating those who perished due to potato blight.

This little-known Revolutionary War fort is supposedly haunted by the ghosts of its past.

A daily replay of the experiment that proved the rotation of the Earth.

Erected in 1697 this Philadelphia bridge is the oldest surviving roadway bridge and perhaps the oldest stone bridge in the United States.