Night photography, outdoor in available light falls in the EV 3 to 5 range at 100 ISO, let's take EV 4 at ISO 100 as a typical value.
With a 400 ISO film, you could take hand-held pictures at 1/8th@f/2.8 free hand. This exposes you to both motion blur and imprecise focusing, as focusing at night, with whatever camera, is risky stuff (if you go for optimum sharpness, that is).
Using a tripod would make things much easier. You can use a ISO 100 film, take pictures in the same situation at 4"@f/8 or, as you use black & white, you can take to luxury to expose even more (8" or 16") to open the shadows more and have more printing options in the darkroom.
Check reciprocity failure of your film. Prefer films which have no reciprocity failure for this kind of use (until 16" or so of exposure).
EV tables: http://en.wikipedia.org/wiki/Exposure_value
PS When using the tripod with these long exposure, beware of ground vibration induced by underground trains, truck, buses, etc. Also consider that during the 16" or so exposure people walking will basically leave almost no trace in the picture. This can be interesting for architectural subject: using long exposure will eliminate the human presence in the picture.