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

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

The first declared National Monument in the United States.

A beautiful geyser under environmental threat.

Medicinal spa created with the discharge from a geothermal energy plant.

San Francisco's newly reopened hands-on science museum.

Four glass boxes hover over 1,000 feet in the air to give visitors an unparalleled view of Chicago.

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

The fairy tale castle of the "fairy-tale king."

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

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

One of the tallest buildings in Iceland, and perhaps, the most visually impressive.

A roaring, awe-inspiring double cascade of icy water flows through woodland Oregon like something out of a Tolkien novel.

Famously misunderstood wonder of the ancient world

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

Macabre astrological automaton clock dating to the late 1400s.

Florida might be at its most surreal in this museum devoted to the famed Spanish artist.

Where manatees are the snowbird vacationers in these balmy Florida springs.

Possibly the most beautiful carillon in the world, set atop Iron Mountain in Florida.

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

The only swimming pool listed on the National Register of Historic Places is emptied and refilled each day with naturally filtered water.

This giant steer-skull edifice refuses to die.

One of the world's largest telescopes, stares into the night sky with two huge mirrors.

This striking public art installation is suspended above a public park, designed to gently move in the breeze.