sleepycity is a website that sets some serious benchmarks. Now, I'll admit I have a personal bias here - sleepycity was what motivated me to get out of my chair and start crawling through drains. It also gave rise to me spending all of my money on a camera (and then another, more expensive one, a year later). The author of this site, dsankt, has journeyed the world doing his thing in drains, on cranes, in tunnels, underground systems (pictured) and more. He has shot in hundreds of locations, he has thousands of beautiful photographs on display and some of his work is incredible.