They tried to institute a rudimentary surveillance system in early NYC. The idea was to mount mirrors in alleys and stairwells and a person would sit in a central location with telescopes. The telescopes were aimed in such a way that you could see up stairs and around corners via the mounted mirrors.
Needless to say, it was an abject failure. Didn't want people to watch? A rock handled those mirrors nicely.
Interestingly, some of the original mirror mounts can still be found in some of the older buildings throughout the city.
One of the old mirror frames:
Interesting... I just read that the observation rooms doubled as late night tryst locations. I guess when you're spying on everyone, people get excited.