Shulchan Aruch Orach Chayim 671:5 rules that one places one's chanukah lights by the door that leads to the reshut harabim, and that if one has a courtyard between his house and the reshut harabim, then one lights at the entrance to the courtyard. If one lives on an upper floor without direct access to the reshut harabim, one places it in the window where it can be seen from the reshut harabim.
How does all this apply to one living in a modern apartment building? Is the entrance from the hallway to his apartment considered "a door that leads to the reshut harabim"? Or is the hallway considered a courtyard, so that the entrance to the building is the entrance to the courtyard?
Or maybe neither of these options work, in which case maybe he is considered like one who lives in an attic and should be lighting by the window? (Note that if that is indeed the solution, then modern tall apartment buildings may run in to the maximum height limit of twenty amot discussed in this question.)