There’s always an element of luck involved in architectural photography as there certainly is in any location photography. You can try to plan things down to the tiniest detail but that’s ultimately a fool’s errand.  The stars simply have to line up. I go by this first building often enough but one day, riding my bike home from an appointment, I noticed the perfect shadow in the white square on the left. At first I didn’t stop but finally turned around and snapped this with my iPhone to remind me to come back. I returned the next day at about the same time with a better camera wondering if I’d get lucky. But no, the window had been closed and reopened to a different angle. The shadow didn’t fit so perfectly. The day before it was a combination of time of day, time of year, and degree to which the window was open. Even if I’d been hired to shoot that building I wouldn’t be able to recreate that shadow without cooperation of the occupants of that space.

The bridge in the second photo was the subject of a job but not when the circus tent was on the other side. I happened to be nearby one day and noticed that the Cirque du Soleil would be there for a week or so. I made a note of it and returned to capture this image. The tent goes so well with the bridge, the dome on the left, and the clock tower. It also seemed fun to shoot just as a plane was flying over. The last shot, of the stairs, was part of an all day job. In that case I kept my eye on the sun and was able to shoot as the sun was streaming in the two windows, an event that lasted only a few minutes. The sunlight tells you more about the space and the fenestration than the shot would otherwise.  It confirms what you suspect about the windows. So, I guess you could say that there are different kinds of serendipity—the real dictionary meaning of the word as pure and simple luck, the kind you come back to create, and the kind that your experience tells you is coming. I still consider them all serendipity because, no matter how you plan it, things can always change.