According to Harav Yosef Sholom
Elyashiv zt"l: (Ashrei Ha'ish)
Lighting a Chanukah Menorah in front
of the City Hall, Parliament
buildings, top of cars or
other public places etc. makes no sense
whatsoever, even if your
intention is to publicize the Neis
of Chanukah.
Chazal instituted פירסומי ניסא, when, where, and
how.
Anywhere else, there is
absolutely no Mitzvah to do.
Those who light there with a ברכה
are עובר on a ברכה לבטלה"
see here especially footnotes:
ReplyDeletehttp://www.chabad.org/holidays/chanukah/article_cdo/aid/3155136/jewish/Why-Do-I-Hear-Blessings-at-Public-Menorah-Lightings.htm