Take another look @ a close-up image of the iconic 'Bat-Signal' on the rooftop of the Chicago 'Daily Planet' exterior set of director Zack Snyder's "Batman v Superman: Dawn Of Justice":
The 'Bat-Signal' is a distress signal device...
... appearing in the various interpretations of the Batman mythos.
It is a specially modified Klieg searchlight with a stylized symbol of a bat attached to the light so that it projects a large Bat emblem on the sky.
The Signal is used as a method of contacting and summoning 'Batman' in the event of a serious crisis...
...and as a weapon of psychological intimidation to super-villains.
Click the images to enlarge and Sneak Peek "Batman v Superman: Dawn Of Justice"...
