in the mountains of Shanxi Province, in Northern China

lie the Luyashan Mountain's Ningwu ice caves,

a spectacle of icicles, ice falls and ice stalagmites.

(energetic music)

These caves are thought to have formed

around three million years ago, during an early ice age.

And while there are many caves like this around the world,

the Ningwu caves are special for one particular reason.

This cave stays frozen all year long.

While temperatures can reach up to 70 degrees outside

in the summer, the temperature inside

never rises above 32 degrees.

Scientists believe this is due

to the cave's natural bowling pin shape,

which traps cold air inside.

Stretching thousands of feet down,

the top 300 feet are open to the public,

with five layers connected by a winding maze of ice stairs,

holes and bridges.

Established as a national park in 2005,

the caves are staged with colorful lights

emphasizing the grandness of this ancient cavern.

It is truly a sight to behold.