Me and my friend live in Peterborough, a land where tall buildings for rooftopping is pretty much nonexistent as most buildings don't surpass 3 stories. We have recently set our eyes on a group of apartment buildings. They were built around the 60s-70s and are still in use. As I have never done a rooftop that is in use, I am wondering if anyone has any advice or tips how to access the roof. I don't want to bring any tools either (lockpicks ect.) Just looking for some cool pics and a fun infiltration.
Chow,
Afro

1 - climb the stairwell
2 - find the door
3 - try and open that door
4 - if it opens, go outside (put something in to stop the door from closing all the way, you may get locked out)
5 - if the door doesn't open, go back down and try again another day

Seriously though, watch for the window washers - if you can figure out what days of the month they wash the windows you can plan your visit around that. I won't get into specifics about what you should do while that door is open in a public thread, but you can probably figure that out.

There are others here much more qualified than I on this subject, but that's my $.02

Now if the roof access is a hatch and not a door, well that's a whole other thing...but watching for window washers may still apply.

What Freaktography said, if you can't figure out how to bypass the door smoothly or if it's not open, leave and try again another day. Don't do anything foolish. If window washers are up there, be sure to stay quiet, check your 6, and if all goes downhill, be as polite as possible; They're all just human beings trying to do their job.