Hidden Area

People may know about this, but I would like to tell the people who don't know cuz its actually kind of fun!

This is all from memory, but I'm pretty sure this is entirely accutate. In Staunton Island (second, or middle island) the mission where you are in the parking lot and those crazy guys all attack you who have dynomite strapped to their chests. There is a wall that you can walk on which leads to a secret area. All you have to do is steal an ambulance and park it sideways against the wall, and jump on the hood, then onto the top of the ambulance and then onto the wall. But be carefull because the top of the wall is very narrow and is easy to fall off, making this process a pain in the a$$. Just keep following the wall, and then I think you come to a point where you would have to sprint to make a jump. Just keep following the path, and then you'll come to an area where you jump down onto the ground, and there will be a sign on the wall that says "You aren't supposed to be here"

Enjoy!