The smallest studio that i have seen in Boston was about 8 years ago. The reason i remember this was because i tried to rent it, and at the time i think it was about 180 square feet at just under $800 a month. I have yet to see anything in Boston that small since, but i doubt we will ever compare to the things you can find in NYC. I saw the below video and this is just crazy.
Let me know if you know of anything this small in Boston and how much it costs!!