If you've walked enough in NYC, eventually you probably have come across sidewalks that are littered with tiny glass circles. Often dirty and faded, these glass circles known as vault lights once served a purpose of giving sunlight into basement factories before electricity. They are remnants of NYC's industrial past and while many have been paved over and removed, some still remain, like this one at the corner of Mott Street and Broome Street in Chinatown/Nolita.
I passed a guy sitting on the sidewalk cleaning these babies. So cool. I snapped this pic above.