The Sages ordained that the Chanukah lights should be lit at the entrance to one's home, facing the street. They should be placed on the left side of the entrance so that the mezuzah is on the right and the Chanukah lights are on the left.
When placing them, one should not place them lower than three handbreadths from the ground nor higher than ten handbreadths but if one placed them higher than ten handbreadths, he has fulfilled the obligation provided that they are not more than twenty amot [arm's lengths] from the ground. All of these regulations were enacted for the purpose of achieving the effect of publicizing the miracle of Chanukah.
The custom in recent generations has been to place the Chanukah lights in a window facing the street. One should not place them on a table in the middle of the room for then one will not have publicized the miracle. If one lives on a high floor and his window is more than twenty amot above the ground, it is preferable to place the Chanukah lights at the entrance to the most heavily used room in the house, on the left side of the entrance.