I've encountered a few pretty bad ones recently.
They built a tall wall out front, and the gate is locked. But move around to the side, and...the wall stops.
While the front gate of this closed wedding hall was opened, I got a quick look in. The golden front doors there are chain locked (not quite visible). But anyway, first you'd have to get inside the fence while no workers are there. So it's two layers of security.
Or you could follow the active alley around to the side of the building, where there's no fence, and go in through these side doors that are totally unlocked.