? of the Day: Who controls our conduct in the civic space?

I was between meetings at a local law firm with a great art collection when it occurred to me I didn't know anything about the sculpture in front of their offices, depicting a small band of symphony musicians playing music... a tribute to our orchestra, I believe. I couldn't learn much about the sculpture because when I went to explore and photography the work, which is in a public seating area surrounded by benches, I was approached by a guard who said the law firm I was visiting had a strict policy against anyone photographing around their offices. I asked the guard why and he said he didn't know, but that was their policy. As a photographer I am always concerned about photographing something near a "homeland security target" like a power plant, where federal forces may mistake me for a terrorist and swoop me away to a prison in Cuba, but in front of a large office building complex containing a law firm, in a public park area... who determines what are the restrictions on the conduct of the public photographing a public sculpture in public? Anyone else ever confronted by security for such seemingly normal public behavior, and where. And where is this sculpture, and what about it must be protected for homeland security? Click read more [1] to see pictures of the setting, which may or may not be illegal... I have no idea whether or not and why.