Three hundred years of preserved Spanish colonial history in San Antonio.

A beautiful geyser under environmental threat.

An architect's childhood fantasy treehouse made real.

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

Historic funicular railway, believed to be the shortest railroad in the world.

Tiki luxury on Nob Hill.

Established in the '60s, a family-owned tropical drink bar founded by Ray Buhen, bartender to the stars.

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

The legendary building that needed ghostly approval before being built.

The massive, incredibly rare instrument is over 11 feet tall with a range so deep it goes lower than humans can hear.

A spiritual vortex among the red rocks in Sedona.

One of the world's tallest statues is also one of its most hated.

World's largest bell sits on the grounds of the Kremlin in Moscow.

A sculpture park of the tossed aside relics of the USSR, from Stalin to a massive Soviet emblem.

The gorgeous entrances into the city's underbelly look more like grand halls than subway stops.

Bridge that died in war and was resurected.

A tiny church on a man-made island in the Adriatic.

These historic defenses ensured the city within would survive hundreds of years of occupations, sieges, and invasions.

This massive subterranean fissure is known as the "underground Grand Canyon."

Castle and secret tunnel withstood a siege until its owner was killed by the Holy Roman Empire, while sitting on the toilet.

An ancient knight and a symbol of the city's freedom.

Longest fortress system anywhere in Europe.

This one-time health resort was used by aristocrats around the world.

A whimsical bridge adorned with decorative dragons.