An artsy hidden staircase leads to breathtaking views of San Francisco.

A marvel of technology a century ago, this disused power station now offers a lovely glimpse into the industrial design of the past.

From Austrians to Nazis to Soviets, this historic Budapest fortress has a history as complex as the city itself.

A series of caves under Castle Hill that once held the prisoner Vlad Tepes, better known as Count Dracula.

This Hungarian castle was built out of cardboard and wood until it proved so popular that it got upgraded to stone.

Museum dedicated to the terror regimes of Hungary.

A 19th century artistocrat's mansion, turned into a library, hidden in a modern library.

Hot springs monkey spa in the middle of Hell's Valley.

An exquisite tunnel of cascading flowers.

Twelve hundred stone carvings guard this off-the-beaten-path Buddhist temple.

The sound of swaying stalks in this stunning grove has been named a governmentally recognized sound.

Small Island off the coast of Greenland.

The 3.8 billion-year-old rock proves that tectonic plates may have been shifting longer than we thought.

A surprisingly beautiful abandoned World War II military base in East Greenland.

Enormous burial mounds of ancient emperors.

The tiny statues form China's only known terracotta army from the Han dynasty.

Where better to stay the night than inside a trio of ancient Chinese deities representing "the good life."

Not one, not two, but three natural bridges remain in this captivating spot post-sinkhole.

270 million year-old forest of stone.

These layered sandstone mountains in China look like they are made of pressed crayons.

The latest in a series of long glass bridges suspended at terrifying heights.

The world's first hotel built in an abandoned water-filled quarry.

A natural arch offers panoramic views of Yangshuo's karst hills.

This abandoned fishing settlement may well be the greenest village in the world.