A century-old hotspot for jazz, frequented by everyone from Charlie Chaplin to Al Capone.

One of the most scenic stretches of road in America winds between some of the country's oldest trees.

Each year these high desert hills are absolutely covered with poppy flowers in a surreal show of nature.

A museum dedicated to the alleged Roswell Incident.

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

The mysterious wonder of an underground waterfall is illuminated by multicolored lights.

The seawater playground of gilded-era San Francisco burned to the ground in 1966.

If drivers cross the rumble strip on this stretch of Route 66 at just the right speed it plays "America the Beautiful."

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

Wild lights and sound effects turn a walk through some caves into an eye-popping 1960s tourist attraction.

One person's lost luggage is another person's treasure.

The world's longest known cave system.

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

This frequently-photographed waterfall takes only a short hike to visit.

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

A self-built castle made by a mysterious man.

This unique structure in suburban Austin is made up entirely of other people's castaways, and constantly changing.

A beautiful geyser under environmental threat.

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

The first declared National Monument in the United States.

Its buzzing collection honors vibrator history.

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.

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

Relics of the 1894 Midwinter Exposition continue to delight visitors today.