What my son saw on the windowsill

So I get an email from my granddaughter Erica, saying, Nanny, Daddy took a picture of  this bird at work! What kind of bird is it?

I thought it must be some sort of hawk, but came up empty. I wondered: could it be a falcon? Nah. Too far-fetched: it's like having a condor land on your office windowsill! But it turned out to be a peregrine falcon. This looks like an immature specimen that was likely hatched this spring, judging by the large feet. But the markings are exact, particularly the head. I've sincere learned that peregrine falcons live all over the world and prefer high office towers for nesting. I guess they feel safe up there. Hawks and owls like urban areas because they are dense with small birds like sparrows and pigeons, and mice hanging around dumpsters. (And bats. Blah.)