Dumpster, stairs to back door (closed or half open) or to a small loading dock, small light over the doors, pipes coming out of the walls, trail of water down the center of the alley from gutter runoff, newspapers laying about, old cans, "billboard" type signs like those advertising a play or cabaret, fire escape ladder hanging down, shadows (day or night), brick/concrete walls, small corrugated overhang over the doors.

Because I like to blow $%&# up.

Don't fear the night.  Fear what hunts at night.