UNESCO World Heritage Sites that I have had the privilege to see in person. It can be seen in Google Maps Street View too. It's a unique geological site created by molten basalt. That's interesting but not as interesting as the myth of its creation. The myth of the Giant's Causeway is the topic of a recently published TED-Ed lesson.
In addition to using the pre-made TED lesson questions, you could follow-up a showing of this video by asking your students to think about why myths like this one are created and how they grow over time.