Look from the center of the map at the cranes, then to the left side of the map. 
Go that side's back left corner. Find the broken scaffolding. Sprint from before 
the ledge, and jump to the left outside yellow vertical railing of the 
scaffolding. This is a hidden ladder. Climb up this railing/ladder to the top of 
the scaffolding. Walk to the right of the scaffolding along the ledge of the 
building. You will eventually reach another scaffolding. Climb onto this 
scaffolding. Walk to the top. Look towards the building, and climb onto the 
higher ledge. Follow that ledge going left. Keep moving forward to reach the 
roof. This is a very good sniper spot. It is recommended you use a Tactical 
Insertion because other players may discover you on your way to the top, or 
while you are up there, and try to kill you. There are also a lot of teddy bears 
on the roof.


X-Men: Last Stand reference