Saying this symbol is masonic and placed there by masons is like saying the capitol L is a masonic symbol placed in the alphabet by a mason because it looks like an oblong square.
The Great Seal of the United States is a patriotic symbol and in the US patriotism is far more popular than it is in some other countries. I notice that the original poster is listed as living in Serbia. If I were a native Serb I may well refuse to conclude that any public display would ever be put there for reasons of patriotism.
In the US patriotism is popular enough we have citizens who confuse it with nationalism, yet our latest internal war or nationalism is so long ago even our grandparents might never have met a Civil War veteran. If I were a native Serb who had seen his own Civil War I may well view any patriotic symbol as crossing the line towards the evils of nationalism and want to look elsewhere for reasons the symbol is in the public eye.
Nope, in the US patriotic symbols are quite common. No matter our jokes in this thread that it's an altar to crass commercialism, it's at least as likely to be a spontaneous act of patriotism by its builder as it is to be a joke about commercialism. In the US we are allowed to do both at the same time. It's a luxury we have from having a national history where patriotism without crossing the line into nationalism is more common than the reverse.
Illuminati symbol? Is beyond my kenn that any American would view it as such. I sort of get why a Serb might prefer the idea to an act of patriotism that is punned together with a joke about commercialism. As an American I see the pun and find it hilarious and artistic.