Where is the dirtiest place you ever visited?

At least once in your entire life you will experience the dirtiest place in your version whether or not it’s on purpose. What and where is that place? What were you doing there? Please describe the condition if you don’t mind.

Mine would be,when I was once working as a volunteer for environmental organization. We were instructed to pick up and choose the best trash-materials that are suitable for recycle. We work in public collecting these thing from one trash bin to another trash bin. At first I can’t stand the smell but I try my best to get used to it. The worst experience would be working in suffocating atmosphere(from vehicles smoke) and foul smell from rotten wet trash. I still can’t stand the smell of wet trash till these days.

(Note: ‘dirty = filthy’ not ‘dirty = naughty’).