All along the streets of New York you’ll see cellar doors open, just like the picture below. How people don’t end up falling down them on a regular basis, I don’t know. They are used to bring supplies into restaurants mostly but seem to be open pretty much all the time.

I did a bit of research to see if there were lots of casualties, but all I could find was this:

http://www.quora.com/How-many-sidewalk-cellar-door-accidents-happen-each-year-in-New-York-City?share=1