Surprise! Here's My Colonoscopy Video!
Özkonak, Nevşehir, Türkiye
No. I'm joking. This is a tunnel I photographed in Turkey.
The people of an ancient civilization would hide underground when their city was under siege, with only a few strategically placed holes open to the surface for ventilation.
It was quite claustrophobic -- being underground in these cramped tunnels -- but still much more pleasant than a colonoscopy, I would imagine.