The Boy Scout motto serves photographers well. By always having a camera with you and always being ready to shoot whatever strikes your fancy, you will inevitably capture some gems. I was walking down lower Broadway when I saw these tourists "holding up" the Red Cube, a sculpture created in 1968 by artist Isamu Noguchi. It's a fun picture and it was gone in a moment. The best camera is the one that is with you, just be prepared to use it.
The "Red Cube" is located on the plaza at 140 Broadway. ISO 400, 1/60th sec. at f5.6, 20mm lens.