Suddenly it seems a lot more crowded. The undergrads have returned. An entire summer of a near-deserted campus and uncrowded streets always makes me forget what it's like when 20,000-odd undergrads innundate the town. I've gone from being one of a half-dozen bikes at the spacious bike racks to barely finding a spot to squeeze my bike in.
For me, the "first week of class" is almost meaningless. I don't TA this semester, there are no meetings or colloquiua this week, one of my classes is attending a colloquium series (and writing a paper on it), and the other only meets once a week. There's a certain temptation to hide in my office and only being forced to recognize the presence of undergrads when classes change and the stairwells are suddenly jam-packed and ringing with noise.