This is one of my personal favourites.
It is outside the city market, just outside the doors that lead outside on the side of brunswick square.
There are lots of concrete block at various heights. A Bike Rail. A large wall that you can climb, and some picnic table. Its a fairly small area, and I have never had any security guards talk to me, and very rarely do I have people talk to me in a negative manner.
Also, To point something out, It is a very symmetrical place.
Things are at equal distences, hights, and lengths from each other. its wonderful.