Me and a friend were messing around, and we wound up in that huge apartment from "A Long Way To Fall". For those who do not recall, its the building were you have to run up 32 flights of stairs, go into a room, only to find the guy has run up onto the roof. When you kill him, you get a cinematic camera of him falling all the way down.

Back on topic;
The room he was meant to be in is on the 2nd last floor. You go in, and one of the doors is closed - the one leading into the poor excuse for a bedroom. You do the glitch here just like the Cluckin' Bell one (one guy jumps on the end of the door, the other gradually closes it, when you start climbing over they open it again) And you turn invisible! You can travel the whole floor, and the whole room. Its faster to take the helicopter up but.
Its with a trio of buildings on the NW coast of Algonquin. Use GTA Hood for a proper map. ENJOY

P.S. Sorry for the lack of a vid, i don't have a capture card.

Link for map to building:
http://grandtheftauto.ign.com/missio...ng-Way-to-Fall