 I'm Anne Strange-Empson. Today, we're headed underground, crawling through caverns, swimming into sea caves, looking at prehistoric cave art tens of thousands of years old. When you enter a cave on your own, you will see that it has a very strong impact on you physically. It's like entering a church. It has an impact on your mind and on your imagination. And it's magical. There is something magical about the underworld. There's this.