When I was a graduate student, working toward my Ph.D., I wouldn't have wanted such proximity, or assumed that this would have resulted in me being a part of the social circle of any of the professors that I worked with, despite the fact that I got along well with them. It's an uneven footing, so to speak, and some of the joys (and trials) in that time of my life were better shared with friends in similar places (or, if professors, not with those in my department). This was true even though one or two of my professors occasionally went to the bar with some Ph.D. students (and I was a part of this). Universities are often wary of or even prohibit professors from fraternizing (being too close) with their students because a) professors have more power than students, which can set up the potential for exploitation, sexual or otherwise; and b) conversely, it can create a situation where a manipulative student can pressure or even blackmail a professor if something inappropriate has occurred. In addition, it can be awkward. The professor may genuinely like the student, but not necessarily want to bring them into their "friend" circle (or vice versa). It's partly a matter of having appropriate boundaries that both parties are sensitive to. Later, I taught at this same university (a few years post-Ph.D.), and discovered some other issues. A faculty member in another area (same department) offered to give me a lift home following a department-wide professional and social event; he became very sexually aggressive once we reached my place, and his (much) greater power was a possible threat to my continued employment. A student of mine who was my age pursued me romantically, and subtly pursued trying to get a better grade than he deserved. Mixing students and faculty living quarters isn't necessarily a good idea! Living in the same apartment building during the Ph.D. years makes it all too easy to make assumptions that may not be true, and to be emotionally vulnerable, particularly if you're the student, or to feel that your private life has been encroached upon if you're the professor. After I was no longer teaching there, I used to occasionally visit the area where the two professors I was closest to had moved. At that point, I felt free to call them, and we would see each other socially. This was not awkward, and was in many ways an ideal (and respectful) way to be a part of each other's lives.