In this episode, we answer a question from 5-year-old Wyatt in Los Angeles and learn about ancient underground cities in Turkey, the subterranean passageways of Montreal and the dug-out houses of Coober Pedy, Australia.

Also in this episode: Why is it so warm underground?

But Why is a show led by you, kids!

You ask the questions and we find the answers. It’s a big interesting world out there. On But Why, we tackle topics large and small, about nature, words, even the end of the world.