Mirrors of any size are outlawed within the city. The exact reason for this decree is unknown, but rumor links it to the Demon-Queen’s supposed magical foresight. Current thought leans towards either the idea that reflections confuse her ability to see beyond the normal confines of space and time, or else that her reflection is baleful for her to behold.
Of course, in a city like Zangiers this just serves to make such items more sought-after. Any decent home will have one or more reflecting pools (and these are completely legal, but any in public places are liable to be the target of destructive vandalism in short order), and many of the secret and/or criminal organizations within the city will not hold a significant meeting without a mirror present.