The idea behind the Chanukiya is to publicize the Chanukah miracle, therefore the Chanukiya should be placed in a publicly visible place so that the outside world can be made aware of it. Additionally, when lighting the Chanukiya, all members of the household should be present so as to publicize the miracle in a private sense too- to one’s family and self.
There are specific laws regarding where one should place the Menorah. They should be placed higher than three tefachim (tefachim are handbreadths and three tefachim is approximately eighteen inches) from the ground and lower than ten tefachim (which measure about five feet).
If one does place the Chanukiya higher than ten tefachim but lower than twenty amot (between thirty and forty feet) then one has fulfilled his obligation but not in the most ideal manner. Anything above twenty amot, and one has not even fulfilled his obligation.
One may ask why we have to be so particular regarding the height at which the Chanukiya is placed. As we explained before, the whole point of the Chanukiya candelabra is in order to publicize the miracles of the Chanukah story. Therefore, if the Chanukiya is placed too high or low to be viewed, this defeats the whole point!
In Talmudic times the Sages fixed that one should place the Chanukiya by the doorpost- with the Mezuzah on the right side and the Chanukiya on the left, surrounding the doorpost with the fulfillment of commandments.
Nowadays, many people live in apartment buildings so the idea of placing the Chanukiya by one’s doorpost isn’t really feasible. Additionally, for Jewish people living outside of Israel, the threat of anti-Semitism is unfortunately also an aspect that prevents one from doing so. Therefore, it has become common practice to place the Chanukiya on one’s windowsill, facing the street. If one’s apartment is at a greater height than twenty amot, Rabbi Kitov states that it is preferable to light at the entrance to the home, because it is more likely to be seen by people there.
Thank G-d today Jewish people can live freely in their land and those who merit to do so have the opportunity to light their Chanukiyot proudly at the entrance of their homes. It is indeed a wonderful sight on the festival of Chanukah to wander around the streets in Israel and to see the hundreds upon hundreds of Chanukiyot that light up the darkness of winter, proudly proclaiming the miracle of Chanukah.
Source
http://www.ou.org/chagim/chanukah/somelaws.htm
